It may be time to go back to cash, stop the fuel pump at $20.05:) every day will be a treasure hunt
The following is what I would expect to find at your local store that maybe worth more than face value:
From 1837 through 1964 the silver percentage was 90% for silver dollars, halves, quarters, dimes.
From 1965 through 1970 half dollars and silver (Eisenhower) dollars were made with a core of 21% silver, clad with an outer layer made from 80% silver.