Pull out this $5 Silver Certificate to pay for something, and you're going to get a lot of attention. It's a Series of 1899 note, which is still legal tender, but instead of Abraham Lincoln in the center, as you'd usually expect to see on a fiver, there's a terrific portrait of Sioux Chief Running Antelope. A very popular piece of large-size U.S. currency, and really difficult to find these days.