I've featured some pretty awesome polymer food jewelry before (see links below). They are so realistic, you almost want to take a bite! Nothing is more scrumptious than the ones which mimic baked goods.
Mo Tipton's polymer clay heart cookie charm tutorial shows how it is done. It is a meticulous how- to as she even demonstrates the 3 different ways to get the cookie shape. You'll have to hop over and find out what she uses to make the clay rough so it looks like a real cookie once it is baked.