The United States penny (or one-cent piece) has never featured a pig on its reverse (back) side. It has featured a Lincoln Memorial since 1959.
However, you might be thinking of a different coin or a collector's item.
To know the actual value of your coin, you need to:
* Identify the country of origin: Many countries have coins with pigs on them.
* Determine the year and mint mark: The year and mint mark can significantly affect the value.
* Assess the condition: Coins in good condition are worth more.
If you're unsure about the value of your coin, it's best to consult a professional coin dealer or numismatist. They can provide accurate information and assess the value based on the coin's features and condition.