The 1964 proof set is the first to contain the Kennedy half dollar and the last until the 1990s to have 90% silver versions of the dime, quarter, and half dollar.
Seated Liberty half dollars were minted from 1839 through 1891 and remain a highly popular -- and scarce -- collectible coin to this day. See their current value here.
The 1950 proof set was the first proof set made by the U.S. Mint since 1942. Featuring silver coins and the now-obsolete Lincoln wheat cent, the 1950 proof set is a popular coin set among coin collectors.
The 1964-D Peace silver dollar is not just a rare U.S. coin -- the government believes none even exist anymore. After all, they were supposedly all melted down, and it's illegal to own a 1964-D Peace dollar, too.
