It's a 1979 D Anthony dollar, also known as a 'Carter Quarter". Jimmy Carter was president when these were first issued and the coins were not popular with the public. They were much smaller than the Eisenhower dollar that preceded this series and many people lost money at stores when they confused them with quarters.
Because they were so unpopular, the Federal Reserve banks had millions worth in $25 and $100 sealed bags, and they started getting rid of them by having the US Postal Service give them out in change in stamp machines.
The only Anthony dollars that have any real value are the S-mint proof coins. Your coin, if it came directly out of a sealed Mint bag, likely has plenty of small scratches called 'bag marks' that keep the value to no more than $2. If you got yours in change, you can spend it. Anyone who kept these in their junk drawers since 1979 made a big mistake. Today, you need $3.53 to buy what that coin would have bought in 1979.