A mint mark on a half dollar is a letter "P", "D", "CC", "O", or "S", usually much smaller than the other letters on the coin's design.
The letters used and their locations vary depending on the coin's date, and up till 1980 US half dollars made in Philadelphia didn't have any mint mark. There's more information at the Related Question.
The mint mark on a Barber Half Dollar is located on the reverse side right under the tail of the eagle.
The first Half dollar with any mint mark was from the New Orleans Mint in 1838.The mint mark is on the reverse under the eagle
The 1920 Half Dollar - aka - Liberty Walking - mint mark of "D" or "S" would be located on the reverse side, just to the left and above the "H" in half dollar.
The mint mark is on the reverse of the coin between the tail and the D in the word dollar.
Sorry, no "F" mintmarks, look at the coin again and post new questin
An uncirculated Philadelphia half from 1972 retails for about $1.
Look at the date again and post new question, the first Walking Liberty half was 1916.
No mint mark indicates that the coin was minted in Philadelphia.
The mint mark on a 1936 Walking Liberty half dollar is located on the reverse [tails] side of the coin in the little "valley" just to the left of the word "HALF" near the edge of the rim.
Half a dollar Depends on the mint mark - if it has an "S" and is in its original packaging it might sell for a couple of dollars.
The mint mark on Franklin half dollars is on the reverse side, just above the Liberty Bell.
Hammer and sickle