San Francisco mint used a small "S" mintmark to identify their coinage in 1939. Look on the reverse at the left side of Monticello, an "S" between the building and the rim is a San Francisco nickel.

How much is a 1939 Nickel no mint worth?

There were only a total of 6.3 million of these coins produced. An average condition coin can be worth $2, while those that are in mint condition can fetch up to $80.

Where is the mint mark on a silver Nickel?

Jefferson Nickel: since 1968, the mint mark follows the date on the obverse. The 35% silver nickels minted between 1942 in 1945 have the mint mark on the reverse above the Monticello building. Between 1938 and 1964 the mint mark is on the reverse on the right-hand side lower corner of Monticello.