Jefferson nickel

Wartime silver nickels, 1942 to 1945 The one nickel worth checking every time you see a 1940s date. To save nickel for the war, these were struck in an alloy that is 35% silver, and the Mint flagged them with a large mint mark above Monticello's dome on the back, including a P for Philadelphia, the first time that mark appeared on a US coin. They are scarce in change now, but a big letter over the building is unmistakable, and the silver content means each one is worth more than its face value.