These pieces are known as Buffalo (usually) or Indian Head nickels. In the first year of issue, 1913, there were two distinct varieties, the first showing the bison on a mound, and the second with the base redesigned to a thinner, straight line.
James Earle Fraser designed this nickel, employing three different Native Americans as models. His initial F is beneath the date. The bison was supposedly modeled after “Black Diamond” in the New York Central Park Zoo.
Matte Proof coins were made for collectors from 1913 to 1916.