Any Buffalo nickel with no mintmark was struck in Philadelphia. Nickels did not have a "P" mintmark until 1980.
The "F" you see under the date is NOT a mintmark, it's the designers James Earle Fraser initial. The mintmark (if it has one) is on the back under "FIVE CENTS". The likely value is 25 cents to $1.00 In addition the coin is called a buffalo nickel or an Indian head nickel, but not "buffalo head" because it shows the entire animal :)
Check under the "FIVE CENTS" on the reverse of the coin. Possible mint marks are:No mint mark = PhiladelphiaD = DenverS = San FranciscoAlso note that the coin is called either a Buffalo Nickel or Indian Head Nickel, but not "buffalo head". After all, it shows the whole buffalo, not just its head!
Assuming the coin is circulated, the 1936-D Indian Head / Buffalo nickel is a very common coin, for a coin in average circulated condition the values are $1.00-$4.00 retail. NOTE: No Buffalo nickel has ever been struck in silver.
If it has one it's on the reverse under FIVE CENTS
The 1930 Indian head (or Buffalo) nickel was only struck at the Philadelphia & San Francisco Mints so it can't have a "D" mintmark. In average circulated condition, it's valued from $1.00-$3.00.
The coin is a Indian Head nickel but is commonly called a Buffalo nickel. 1938 was the last year the coins were made and all of them were struck at the Denver Mint so there is a "D" mintmark on the reverse under FIVE CENTS. None of them were ever struck in silver, most coins have values of $3.00-$5.00
Coins have mintmarks not codes. Mintmarks on Buffalo nickels are on the reverse under FIVE CENTS and can only be a D or S.
If it has one, it's on the reverse under the words FIVE CENTS and can only be an "S"
If it has any mintmarks. They are very small and located on the reverse, under FIVE CENTS.
Please check your coin again. It says FIVE CENTS under the buffalo so it's a nickel rather than a penny, and is called either an Indian head nickel or a buffalo nickel; both names are equally common. There's more information at the Related Question.
The "F" is not a mintmark, it's the designer James E. Fraser initial and is on all Buffalo nickels, mintmarks are on the back of the coin under the words FIVE CENTS. Value for circulated coins are 25 cents to $1.00
The "F" under the date of the buffalo nickel isn't a mintmark, it's the initial of the coin's designer, James E. Fraser. The mintmark position is on the back under the words FIVE CENTS. Please see the question "What is the value of a 1927 US nickel?" for more information.