You can safely trade items using the Whyville Trading Post!
Brett takes 5 clams per trade for the use of his room, but you'll be safe from scammers and con artists who might claim to sell you an Elmo but leave you high-and-dry.
Here, you see what your partner is offering, and the trade doesn't happen until you both agree.
There are lots of trading rooms. Decide on a room number with your friend and then navigate to that room.
To trade, sit in one chair and have your trading partner sit in the other chair.
As soon as you sit down, a window will pop up with a list of all the parts you can trade.
Assemble the items you want to trade. You can offer up to 3 items, including a pile of clams.
When you have your offer ready, press the Set button in the pop-up window.
Your partner will do the same. If you agree with the trade, press the Agree button.
When both traders press Agree the trade is made. Wait a few seconds, and you'll be sent back to Brett to hear the result of your trade.