Wheat Reverse cents were produced at the Philadelphia, Denver, and San Francisco mints. In general, cents from Philadelphia are well made; those from Denver and San Francisco are often poorly struck from worn dies. Key dates in the series include the... 1909-S VDB, 1914-D, and 1922 "Plain", plus the 1909-S and 1931-S. Interesting varieties include the 1917 and 1936 Doubled Die Obverse. - Ron Guth