Chinatown Half Dollar
The magician places a card in a spectator's hand to act as a table. A half-dollar and Chinese coin, complete with a hole through it, are placed on top of the card. All is covered with a handkerchief. One of the coins is removed, shown to the spectator and placed into your pocket. When the spectator is asked to identify the remaining coin. The spectator sees that the coins mysteriously change places.
This can be repeated and all is examinable at both the beginning and end of the effect.