I was searching through coin rolls today when I found a 1974 Nickel. The Nickel had no mint mark on the front therefore indicating that it was from the Philly mint. The interesting thing was that when I turned the coin over it had the P mint mark like what was produced in the 40's. The P was not a raised P but was actually indented in the reverse. I have not been collecting coins for very long and therefore I don't know if this was common or not because it is the first one of it's kind that I've ever seen.