In the old days, people carved nickels to pass the time. Some people still carve nickels today.
Folk artists have used just about every material on earth. That includes earth and dirt, as last week linkers were interested to see perfectly round, highly polished balls of dirt as folk art from Japan.Link (Thanks, axlrosen!)
When the US first minted the buffalo nickel in 1913, the practice of carving a new face onto the nickel was started, because the coin was thick and its metal was malleable.