How much is a 1988 silver penny worth?

The U.S. has never struck cents in silver. Among other things, all silver was removed from circulating coins during the period 1964-69, so even higher denominations like dimes and halves are all made of cupronickel.

Since 1983 cents have been struck in copper-plated zinc, so there are 2 possibilities:

> Someone dipped your coin in acid and etched away the copper plating. This is a damaged coin worth only 1¢

> The coin was accidentally left out of the plating process at the mint. This is a true error and could be worth $50 to $100.

However, you'll need to have a coin expert evaluate your coin in person to determine what you have.