I have been metal detecting and collecting coins for years and came across a strange coin. It is a 1965 U.S. Quarter that looks and feels silver. It is in rough shape and is very tarnished. Looks and sounds just like every other silver quarter I have found yet I thought they stopped making them in 1964. The edge is one color (silver) and the coins has that distinctive silver sound to it. Coin weighs 6.19 grams. Any one ever hear of one of these and if so is it valuable??