WARNING, LOOOOOOONG POST. 
There are loads of codes for this game, I picked out the most useful ones so far. If there's any requests for a specific code, feel free to post.
The Villager Affection code took a long time to figure out. I had to compare offset values from Back To Nature codes on the PSX and recalculate the difference between the PSP version as well again to figure them out. Same goes for the Harvest Sprites working skills.
Weather Mod (Next Day)
Misc. Codes
Note 1: With the Tool Max Code you still need to go to Saibara to upgrade them to Mystrile tools.
Note 2: Max Resources = 999 Chicken Feed, Fish Food, Fodder and Lumber.
Note 3: The Intelligence and Stamina Code might not work. It's hard to test this code, because they're invisible values in the game. Basically the higher their values they are, the higher your chances are of winning the Dog- and Horse Races.
Note 3B: Just tested it in Dog Race, the dog was performing PERFECTLY, this indicates the codes do work fine. Because I made sure I didn't train the dog's intelligence this time around.
Rucksack Mod Codes
Note: Enable one code at a time. With the 'Item In Hand' codes you'll basically be able to give infinite gifts to anyone.
Some codes made with this
Girl Affection Codes (All Girls at once)
Girl Affection Codes (Individual Girls)
Villager & Baby Affection Codes
Note: Being friends with the villagers is great. You can enter their houses, and you'll be able to enter shops much earlier than usual. Example: You can actually enter the Super Market at 8AM instead of 9AM.
Pets & Animals Affection Codes
Animals Fed
Harvest Sprite Codes
Note 1: The reason I set it to 2 days is because if you set it to 1 day, they won't show up for work. Just enable the code and they'll always be there for work.
Note 2: The 'skill' levels determine how well they perform their job. At max level (FF) they'll basically do things at lightning speed.
Note 3: For the Sprite Job codes, only enable one at a time. You decide what you want them to do. I made a bunch of preset codes. (I use the 'All Jobs' code myself in my game. But for Winter season you can just let all of them take care of your animals.
0 = Free, 1 = Harvest, 2 = Water Crops, 3 = Harvest (Water Can Icon), 4 = Take care of animals.
There are loads of codes for this game, I picked out the most useful ones so far. If there's any requests for a specific code, feel free to post.
The Villager Affection code took a long time to figure out. I had to compare offset values from Back To Nature codes on the PSX and recalculate the difference between the PSP version as well again to figure them out. Same goes for the Harvest Sprites working skills.
Weather Mod (Next Day)
Code:
_C0 Rain the next day
_L 0x001BC1B2 0x00000001
_C0 Sun the next day
_L 0x001BC1B2 0x00000000Misc. Codes
Note 1: With the Tool Max Code you still need to go to Saibara to upgrade them to Mystrile tools.
Note 2: Max Resources = 999 Chicken Feed, Fish Food, Fodder and Lumber.
Note 3: The Intelligence and Stamina Code might not work. It's hard to test this code, because they're invisible values in the game. Basically the higher their values they are, the higher your chances are of winning the Dog- and Horse Races.
Note 3B: Just tested it in Dog Race, the dog was performing PERFECTLY, this indicates the codes do work fine. Because I made sure I didn't train the dog's intelligence this time around.
Code:
_C0 Infinite Stamina
_L 0x001B2EC2 0x000000C8
_C0 Maximum Stamina = 200
_L 0x001B2EC4 0x000000C8
_C0 No Sickness
_L 0x001B2EC6 0x00000000
_C0 Infinite Money
_L 0x201B2F0C 0x0098967F
_C0 9999 Medals Horse Race
_L 0x101B2F10 0x0000270F
_C0 Low Expenses
_L 0x201B26B0 0x00000000
_C0 Tools Ability: Max
_L 0x101B2EF0 0x0000FFFF
_L 0x101B2EF2 0x0000FFFF
_L 0x101B2EF4 0x0000FFFF
_L 0x101B2EF6 0x0000FFFF
_L 0x101B2EF8 0x0000FFFF
_C0 Infinite Seeds & Water
_L 0x001B2F38 0x00000064
_C0 Max Resources
_L 0x101B21F0 0x000003E7
_L 0x101B21EE 0x000003E7
_L 0x101B21EA 0x000003E7
_L 0x101B21E8 0x000003E7
_C0 Dog: Max Intelligence
_L 0x001B6F40 0x000000FF
_C0 Horse: Max Stamina
_L 0x001B7030 0x000000FFRucksack Mod Codes
Note: Enable one code at a time. With the 'Item In Hand' codes you'll basically be able to give infinite gifts to anyone.
Code:
_C0 Slot 1 = ???
_L 0x101B2F70 0x00000YYY
YYY = Item ID (Hex)Some codes made with this
Code:
_C0 Slot 1 = Wine
_L 0x101B2F70 0x0000009F
_C0 Slot 1 = Large Fish
_L 0x101B2F70 0x000000A1
_C0 Slot 1 = Chocolate
_L 0x101B2F70 0x000000F3
_C0 Item in Hand: Truffle
_L 0x101B2F3A 0x0000005C
_C0 Item in Hand: Perfume
_L 0x101B2F3A 0x00000100
_C0 Item in Hand: Bracelet
_L 0x101B2F3A 0x000000F7
_C0 Item in Hand: Chocolate
_L 0x101B2F3A 0x000000F3
_C0 Item in Hand: Chocolate Cake
_L 0x101B2F3A 0x000000F5Girl Affection Codes (All Girls at once)
Code:
_C0 All Girls Black Hearts
_L 0x101B7C50 0x00000001
_L 0x101B83A0 0x00000001
_L 0x101B8748 0x00000001
_L 0x101B906C 0x00000001
_L 0x101B9B64 0x00000001
_C0 All Girls Purple Hearts
_L 0x101B7C50 0x00003FFF
_L 0x101B83A0 0x00003FFF
_L 0x101B8748 0x00003FFF
_L 0x101B906C 0x00003FFF
_L 0x101B9B64 0x00003FFF
_C0 All Girls Light Blue Hearts
_L 0x101B7C50 0x00004E20
_L 0x101B83A0 0x00004E20
_L 0x101B8748 0x00004E20
_L 0x101B906C 0x00004E20
_L 0x101B9B64 0x00004E20
_C0 All Girls Green Hearts
_L 0x101B7C50 0x00007530
_L 0x101B83A0 0x00007530
_L 0x101B8748 0x00007530
_L 0x101B906C 0x00007530
_L 0x101B9B64 0x00007530
_C0 All Girls Yellow Hearts
_L 0x101B7C50 0x00009C40
_L 0x101B83A0 0x00009C40
_L 0x101B906C 0x00009C40
_L 0x101B9B64 0x00009C40
_L 0x101B8748 0x00009C40
_C0 All Girls Orange Hearts
_L 0x101B7C50 0x0000C350
_L 0x101B83A0 0x0000C350
_L 0x101B906C 0x0000C350
_L 0x101B9B64 0x0000C350
_L 0x101B8748 0x0000C350
_C0 All Girls Red Hearts
_L 0x101B7C50 0x0000FFFF
_L 0x101B83A0 0x0000FFFF
_L 0x101B906C 0x0000FFFF
_L 0x101B9B64 0x0000FFFF
_L 0x101B8748 0x0000FFFFGirl Affection Codes (Individual Girls)
Code:
_C0 Karen Black Heart
_L 0x101B7C50 0x00000000
_C0 Ann Black Heart
_L 0x101B83A0 0x00000000
_C0 Elli Black Heart
_L 0x101B8748 0x00000000
_C0 Mary Black Heart
_L 0x101B906C 0x00000000
_C0 Popuri Black Heart
_L 0x101B9B64 0x00000000
_C0 Karen Purple Heart
_L 0x101B7C50 0x00003FFF
_C0 Ann Purple Heart
_L 0x101B83A0 0x00003FFF
_C0 Elli Purple Heart
_L 0x101B8748 0x00003FFF
_C0 Mary Purple Heart
_L 0x101B906C 0x00003FFF
_C0 Popuri Purple Heart
_L 0x101B9B64 0x00003FFF
_C0 Karen Light Blue Heart
_L 0x101B7C50 0x00004E20
_C0 Ann Light Blue Heart
_L 0x101B83A0 0x00004E20
_C0 Elli Light Blue Heart
_L 0x101B8748 0x00004E20
_C0 Mary Light Blue Heart
_L 0x101B906C 0x00004E20
_C0 Popuri Light Blue Heart
_L 0x101B9B64 0x00004E20
_C0 Karen Green Heart
_L 0x101B7C50 0x00007530
_C0 Ann Green Heart
_L 0x101B83A0 0x00007530
_C0 Elli Green Heart
_L 0x101B8748 0x00007530
_C0 Mary Green Heart
_L 0x101B906C 0x00007530
_C0 Popuri Green Heart
_L 0x101B9B64 0x00007530
_C0 Karen Yellow Heart
_L 0x101B7C50 0x00009C40
_C0 Ann Yellow Heart
_L 0x101B83A0 0x00009C40
_C0 Elli Yellow Heart
_L 0x101B8748 0x00009C40
_C0 Mary Yellow Heart
_L 0x101B906C 0x00009C40
_C0 Popuri Yellow Heart
_L 0x101B9B64 0x00009C40
_C0 Karen Orange Heart
_L 0x101B7C50 0x0000C350
_C0 Ann Orange Heart
_L 0x101B83A0 0x0000C350
_C0 Elli Orange Heart
_L 0x101B8748 0x0000C350
_C0 Mary Orange Heart
_L 0x101B906C 0x0000C350
_C0 Popuri Orange Heart
_L 0x101B9B64 0x0000C350
_C0 Karen Red Heart
_L 0x101B7C50 0x0000FFFF
_C0 Ann Red Heart
_L 0x101B83A0 0x0000FFFF
_C0 Elli Red Heart
_L 0x101B8748 0x0000FFFF
_C0 Mary Red Heart
_L 0x101B906C 0x0000FFFF
_C0 Popuri Red Heart
_L 0x101B9B64 0x0000FFFFVillager & Baby Affection Codes
Note: Being friends with the villagers is great. You can enter their houses, and you'll be able to enter shops much earlier than usual. Example: You can actually enter the Super Market at 8AM instead of 9AM.
Code:
_C0 Villagers Max Affection
_L 0x001B78A6 0x000000FF
_L 0x001B7A7A 0x000000FF
_L 0x001B7E22 0x000000FF
_L 0x001B7FF6 0x000000FF
_L 0x001B81CA 0x000000FF
_L 0x001B8572 0x000000FF
_L 0x001B891A 0x000000FF
_L 0x001B8AEE 0x000000FF
_L 0x001B8CC2 0x000000FF
_L 0x001B8E96 0x000000FF
_L 0x001B923E 0x000000FF
_L 0x001B9412 0x000000FF
_L 0x001B95E6 0x000000FF
_L 0x001B97BA 0x000000FF
_L 0x001B998E 0x000000FF
_L 0x001B9D36 0x000000FF
_L 0x001B9F0A 0x000000FF
_L 0x001BA0DE 0x000000FF
_L 0x001BA2B2 0x000000FF
_L 0x001BA486 0x000000FF
_L 0x001BAA02 0x000000FF
_L 0x001BABD6 0x000000FF
_L 0x001BADAA 0x000000FF
_L 0x001BAF7E 0x000000FF
_L 0x001BB152 0x000000FF
_L 0x001BB4FA 0x000000FF
_L 0x001BB6CE 0x000000FF
_C0 Baby: Max Affection
_L 0x001BB8A2 0x000000FFPets & Animals Affection Codes
Code:
_C0 Barn Animals Max Hearts
_L 0x001B5EBA 0x000000FF
_L 0x001B5F72 0x000000FF
_L 0x001B602A 0x000000FF
_L 0x001B60E2 0x000000FF
_L 0x001B619A 0x000000FF
_L 0x001B6252 0x000000FF
_L 0x001B630A 0x000000FF
_L 0x001B63C2 0x000000FF
_L 0x001B647A 0x000000FF
_L 0x001B6532 0x000000FF
_L 0x001B65EA 0x000000FF
_L 0x001B66A2 0x000000FF
_L 0x001B675A 0x000000FF
_L 0x001B6812 0x000000FF
_L 0x001B68CA 0x000000FF
_L 0x001B6982 0x000000FF
_L 0x001B6A3A 0x000000FF
_L 0x001B6AF2 0x000000FF
_L 0x001B6BAA 0x000000FF
_L 0x001B6C62 0x000000FF
_C0 Chicken Max Hearts
_L 0x001B57B2 0x000000FF
_L 0x001B5866 0x000000FF
_L 0x001B591A 0x000000FF
_L 0x001B59CE 0x000000FF
_L 0x001B5A82 0x000000FF
_L 0x001B5B36 0x000000FF
_L 0x001B5BEA 0x000000FF
_L 0x001B5C9E 0x000000FF
_L 0x001B5D52 0x000000FF
_L 0x001B5E06 0x000000FF
_C0 Dog & Horse Max Hearts
_L 0x001B6EAA 0x000000FF
_L 0x001B6F9A 0x000000FFAnimals Fed
Code:
_C0 Chickens Fed
_L 0x001B27BE 0x00000001
_L 0x001B27BF 0x00000001
_L 0x001B27C0 0x00000001
_L 0x001B27C1 0x00000001
_L 0x001B27C2 0x00000001
_L 0x001B27C3 0x00000001
_L 0x001B27C4 0x00000001
_L 0x001B27C5 0x00000001
_L 0x001B27C6 0x00000001
_L 0x001B27C7 0x00000001
_C0 Barn Animals Fed
_L 0x001B27A8 0x00000001
_L 0x001B27A9 0x00000001
_L 0x001B27AA 0x00000001
_L 0x001B27AB 0x00000001
_L 0x001B27AC 0x00000001
_L 0x001B27AD 0x00000001
_L 0x001B27AE 0x00000001
_L 0x001B27AF 0x00000001
_L 0x001B27B0 0x00000001
_L 0x001B27B1 0x00000001
_L 0x001B27B2 0x00000001
_L 0x001B27B3 0x00000001
_L 0x001B27B4 0x00000001
_L 0x001B27B5 0x00000001
_L 0x001B27B6 0x00000001
_L 0x001B27B7 0x00000001
_L 0x001B27B8 0x00000001
_L 0x001B27B9 0x00000001
_L 0x001B27BA 0x00000001
_L 0x001B27BB 0x00000001Harvest Sprite Codes
Note 1: The reason I set it to 2 days is because if you set it to 1 day, they won't show up for work. Just enable the code and they'll always be there for work.
Note 2: The 'skill' levels determine how well they perform their job. At max level (FF) they'll basically do things at lightning speed.
Note 3: For the Sprite Job codes, only enable one at a time. You decide what you want them to do. I made a bunch of preset codes. (I use the 'All Jobs' code myself in my game. But for Winter season you can just let all of them take care of your animals.
0 = Free, 1 = Harvest, 2 = Water Crops, 3 = Harvest (Water Can Icon), 4 = Take care of animals.
Code:
_C0 2 Days Left Working
_L 0x001BBB9C 0x00000002
_L 0x001BBC94 0x00000002
_L 0x001BBD8C 0x00000002
_L 0x001BBE84 0x00000002
_L 0x001BBF7C 0x00000002
_L 0x001BC074 0x00000002
_L 0x001BC16C 0x00000002
_C0 Max Sprites Affection
_L 0x001BBAFE 0x000000FF
_L 0x001BBBF6 0x000000FF
_L 0x001BBCEE 0x000000FF
_L 0x001BBDE6 0x000000FF
_L 0x001BBEDE 0x000000FF
_L 0x001BBFD6 0x000000FF
_L 0x001BC0CE 0x000000FF
_C0 Sprites: Max Harvest Skill
_L 0x001BBB96 0x000000FF
_L 0x001BBC8E 0x000000FF
_L 0x001BBD86 0x000000FF
_L 0x001BBE7E 0x000000FF
_L 0x001BBF76 0x000000FF
_L 0x001BC06E 0x000000FF
_L 0x001BC166 0x000000FF
_C0 Sprites: Max Water Skill
_L 0x001BBB98 0x000000FF
_L 0x001BBC90 0x000000FF
_L 0x001BBD88 0x000000FF
_L 0x001BBE80 0x000000FF
_L 0x001BBF78 0x000000FF
_L 0x001BC070 0x000000FF
_L 0x001BC168 0x000000FF
_C0 Sprites: Max Animal Skill
_L 0x001BBB9A 0x000000FF
_L 0x001BBC92 0x000000FF
_L 0x001BBD8A 0x000000FF
_L 0x001BBE82 0x000000FF
_L 0x001BBF8A 0x000000FF
_L 0x001BC072 0x000000FF
_L 0x001BC16A 0x000000FF
_C0 Sprites Job: Harvest
_L 0x001BBBA0 0x00000001
_L 0x001BBC98 0x00000001
_L 0x001BBD90 0x00000001
_L 0x001BBE88 0x00000001
_L 0x001BBF80 0x00000001
_L 0x001BC078 0x00000001
_L 0x001BC170 0x00000001
_C0 Sprites Job: Water
_L 0x001BBBA0 0x00000002
_L 0x001BBC98 0x00000002
_L 0x001BBD90 0x00000002
_L 0x001BBE88 0x00000002
_L 0x001BBF80 0x00000002
_L 0x001BC078 0x00000002
_L 0x001BC170 0x00000002
_C0 Sprites Job: Water & Harvest
_L 0x001BBBA0 0x00000002
_L 0x001BBC98 0x00000002
_L 0x001BBD90 0x00000002
_L 0x001BBE88 0x00000002
_L 0x001BBF80 0x00000001
_L 0x001BC078 0x00000001
_L 0x001BC170 0x00000001
_C0 Sprites Job: Animal Care
_L 0x001BBBA0 0x00000004
_L 0x001BBC98 0x00000004
_L 0x001BBD90 0x00000004
_L 0x001BBE88 0x00000004
_L 0x001BBF80 0x00000004
_L 0x001BC078 0x00000004
_L 0x001BC170 0x00000004
_C0 Sprites Job: All Jobs
_L 0x001BBBA0 0x00000002
_L 0x001BBC98 0x00000002
_L 0x001BBD90 0x00000001
_L 0x001BBE88 0x00000004
_L 0x001BBF80 0x00000001
_L 0x001BC078 0x00000002
_L 0x001BC170 0x00000002