1856 Flying Eagle Penny
The US mint decided that the size of the penny should be reduced in 1856. This came from the price of copper rising so much that the penny would have cost more than one cent to produce. Before this change, a penny was 19 millimeters in diameter, which is almost as big as the current nickel.
Bronze 1943 Lincoln Penny
The bronze version of the 1943 Lincoln penny has been sold at auctions for an astounding amount of $204,000. This penny can accrue such value despite not being in mint condition. These pennies were mistakenly minted in bronze in the year of 1943.