I got a cool birthday present that had these nifty eco-friendly packing peanuts in the box. I remember my kids having these things as a craft supply! (The ones the kids had were called Magic Nuudles) They are made of cornstarch (I'm pretty sure) and stick together with a little bit of water. They dissolve completely and go safely down the drain when you are done with your creation.
Today I took four of the green ones and made a turtle.