It's only valuable if it's a 1939-D or -S, because there weren't as many made that year.
The mint mark on a 1939 Jefferson Nickel is located on the obverse (tails) side of the coin, just to the right of Monticello (the building) between the rim and the building. If there is no mark there then the coin was produced at the U.S. Mint facility in Philadelphia, Pennsylvania.
S is a southbay ny mark. D is a denver mint.
D. S. Mirsky died in 1939.
D. S. Satyaranjan was born on 1939-01-19.
Please post a new question with the coin's denomination. If you can find a small D or S mint mark on it include that detail as well.
It's worth between 10 cents and a couple dollars depending on condition. The '39-D or S are worth a little more.
The value depends on the grade of the coin, the 1939-S Lincoln is not rare, retail values are from 25 cents to $1.50 for circulated coins.
If you mean Mintmarks? Look for a large P, D, or S above the dome of Monticello on the reverse of the coin.
From 1968 to date. The mintmark's will be on the obverse (front) of the coin, to the right of the hair ribbon.
Franklin D. Roosevelt Harry S. Truman Dwight D. Eisenhower
1928-D $3 to $35,000 depending upon the condition of the coin. 1928-S $3 to $85,000 depending upon the condition of the coin.