Please post a new question with the coin's date.
There can't be a 1966-S nickel because the Mint didn't use any mint marks from 1965 to 1967.
If your coin has a "S" mint mark on it means that it was made at the San Francisco mint in California.
If the mint mark is a D the nickel is probably worth no more than a dollar. If the mint mark is an S it could be worth around $3.00 By the way, there is no such thing as a 1938 liberty nickel. The only nickels minted in 1938 were buffaloes and Jeffersons.
5 cents.
If it was found it pocket change spend it
It depends on the type. There were two types: silver-clad and a copper-nickel-clad. Silver-clad contains 0.14792 ounces of pure silver. All have an S mint mark. Copper-nickel-clad does not contain any silver. They can have a D, S, or no mint mark.
If circulated condition its worth about 25 cents if ok quality. If it has a d mint mark about 4.00. If S mint mark about 2.00. If un circulated double all the prices
Unless it's uncirculated, 5 cents. Nickels from Philadelphia did not carry a P mint mark until 1980. FWIW, San Francisco did not strike any coins for circulation between 1956 and 1967 inclusive, so a 1959-S nickel would not be possible.
With no mint mark under the words FIVE CENTS: $1 if very worn, $4 with moderate wear. With a D mint mark, $8-30 With an S, $4-25
On a 1962 nickel, the mint mark is located on the reverse side of the coin, to the right of the building depicted in the center. It can either be a "D" for Denver or an "S" for San Francisco, depending on where the coin was minted. If there is no mint mark, it was minted in Philadelphia.
The S mint on this and any U.S. coin means it was struck in San Francisco. The link below shows all mints and their letter marks.
Yes they are, all "S" Mint 1971 & 1972 Eisenhower dollars are 40% silver, but ONLY for those two years. In 1973 the Mint added copper-nickel clad "S" Mint coins along with the 40% "S" Mint silver coins