PCGS 2000-P Massachusetts quarter missing clad layer reverse. The coin is copper on the reverse side due to the clad layer missing before strike. MS64 Red/Brown
PCGS 2005-D California quarter reverse missing clad layer. The coin is copper on the reverse due to the outer nickel layer missing before the coin was struck.
California is a very scarce state...
2000-P 25c Massachusetts quarter reverse missing clad layer (minor hints of nickel retained on the coin's reverse.) The coin is about 95% copper and 5% nickel on the reverse.