You need to add the year. An S mintmark tells us nothing.
The buffalo is the back. The front is an Indian head.
about 35 cents
There is a buffalo on the back of US nickels.
a 1920 buffalo nickel is worth about 2.50 because it's not that rare
a buffalo
buffalo
Buffalo or Indian Head nickels were minted in the US from 1913 to 1938.
1913 is when the US mint started making buffalo nickels. Remember, the coin is called a "buffalo nickel" or an "Indian Head nickel" but not "buffalo head" because it shows the whole animal on the back.
In average condition, both coins are only worth their face value.
The "f" is not a mintmark but rather an initial. With out a date it is impossible to tell the value of your coin. Most buffalo or Indian head nickels aren't worth much. Post a new question and structure it like this to ensure an answer- "What is the value of a <date> US nickel" or " What is a <date> US nickel worth".
These coins are called Indian head nickels or buffalo nickels but not "buffalo head". After all, they show the whole buffalo on the back, not just its head! Please see the question "What is the value of a 1929 US nickel?" for more information.
Indian head (buffalo) nickels were minted from 1913 to 1938.