Hello, John --

The mintmarks for your Eisenhower dollars would be found under Eisenhower's bust over the right side of the date; that is, if there is any mintmark to be found. Philadelphia-minted Eisenhower dollars did not contain a mintmark. The "Denver" mintmark is a "D" and an "S" mintmark indicates San Francisco.

If your coins have no mintmark (Philadelphia) or a "D" (Denver), they are made from copper-nickel clad and are worth approximately $1.05 to $1.15 if worn. Many "S"-mintmark dollars (San Francisco) are made from a 40% silver composition and their values can be found here:

1971 - https://coinvalues.com/eisenhower-dollar/1971
1972 - https://coinvalues.com/eisenhower-dollar/1972
1973 - https://coinvalues.com/eisenhower-dollar/1973
1974 - https://coinvalues.com/eisenhower-dollar/1974
1976 - https://coinvalues.com/eisenhower-dollar/1976

The only way to tell whether or not an S-mint Ike dollar is made from silver is to weigh the coin; if it's 24.59 grams, it's made from silver; copper-nickel clad pieces come in at 22.68 grams.

The green patina is unfortunately not a desirable thing; it's a sign of PVC corrosion caused by being stored in a plastic holder that contains polyvinylchloride, a substance known to cause damage to coins. I suggest keeping this coin away from any others you have.

I hope this info is helpful to you!
Josh @ CoinValues