Peanuts

Peanuts are botanically a legume, not a nut, but everybody knows that. There is a guessing game you can play with peanuts. When you split the peanut itself (not the shell) in half, one of the halfs gets an extra bit on an edge, which is actually the embryo. The game is to guess which half will get it.
See Also: http://en.wikipedia.org/wiki/Peanut

link to this puzzle