Roarin' 20's S-Mint Mercury Deal
The decade of the 1920's saw an economic recession that kept coin mintages way down until 1927 or so. The Mercury Dime was made at San Francisco in only 8 years:
1920-S
1923-S
1924-S
1925-S
1926-S (Key Date)
1927-S
1928-S
1929-S
That's 8 coins, including the key 1926-S, all nice circulated grade.