Your photos are too small to see any details, but from what you are describing it sounds like you have a 1976P Eisenhower dollar. There are 2 types for this year as you stated, but neither are rare by any means.
As for missing the Mint Mark. This is not the case. It is simply that Dollar coins minted in Philly in 1976 had no mint marks. This is how we know where they were minted. No MM means Philly.






















