1 Dollar (National Baseball Hall of Fame)

The First Coin America Made That Wasn't Flat

For more than two centuries, every coin the United States made was flat. Then in 2014 the Mint cupped one into a dome — concave on the front, bulging like a baseball on the back — and put a worn leather glove on the heads side. It was the first curved coin in American history, and it sold out in about two weeks.