G. Shark Codes
If you have a friend who also has Harvest Moon 2, you can trade items from Mary's computer via your Gameboy gamelink cable. You can't complete her Plant picture book if you don't trade with someone of the opposite gender to get the seeds that you wouldn't normally get.
To activate the Trade Center, hook together your Gameboys using the gamelink cable and head to Mary's Library. One of the options she has is called "Communicate". You and your friend must both select "Communicate" in order to enter the Trade Center. Before you can continue on, you are prompted to save your game. Save your games and the two of you will be linked together to trade.
One of the benefits of animal trading is that it's the only way to get a Golden Chicken. Just trade a chicken (or give as a gift) to your friend and magically it becomes a Golden Chicken. If you want the Golden Chicken back, you have to leave the Trade Center and relink up. If you immediatly trade the chicken back it won't be golden. The only restriction would be if you want to trade sheep. Your friend must have the Sheep Pen built in order to accept a sheep from you.
You need to trade Herb and Flower seeds from another gender's game in order to fill in the missing pages of Mary's Plant book. If your farmer is a boy you'll need to trade with a girl famer game in order to get Rosemary, Camomile, Orchid, and Lavender seeds. If your farmer is a girl you'll need to trade with a boy farmer game to get Sage, Saffron, Geranium, and Primrose seeds. You can also trade regular crop seeds too like Tomato and Brocolli seeds. To trade seeds just select which seed you want to trade and wait for your friend to select his/her seed. Then just "yes" to the confirmation and the save. You can only trade one seed at a time though, so if you want four Primrose seeds from your friend you're going to have to trade four of your seeds, one at a time, for the four Primrose seeds.
If you are missing pictures out of your fish or bug picture book, you can trade with a friend to fill in the blanks. Trading bugs or fish doesn't remove the picture out of your own picture book, it just adds into theirs.
If you want you can also trade your pet with your friend. You would get your friend's pet in return. There's no giving away pets as "gifts" since the point is to swap pets with your friends.
One of the special items in the game is the Treasure Map, which you receive one half of. In order to complete the map, you have to combine the map pieces with a friend who also has part of the Treasure Map.
Choosing this closes the link between your friend and takes you back to Mary's Library.