"Hobo nickels" were a type of folk art common during the Depression. The artist would alter the features of the Indian on the Buffalo nickel (usually; sometimes other coins were used, or the bison on the reverse would be carved up) and turn him into a soldier, a clown, a hobo, or whatever other character the artist chose. They were then sold to raise money.
You can see some examples on collector sites, like
http://www.hobonickels.org/