There is not always a mint mark on coins. If your coin does not have a mintmark it means that it was made at the Philadelphia mint in Pennsylvania.
In G-4 $6.00 to $185.00 in MS-60
its from the phillidelphia mint
a quarter
made in the Philadelphia Mint
No mint mark means it was minted in Philadelphia. The quarter is worth exactly 25 cents.
On the 1979 quarter, the mint mark is located on the reverse side of the coin, just to the right of the eagle's tail. It can be either "D" for the Denver Mint or "P" for the Philadelphia Mint, though Philadelphia coins from that year typically do not have a mint mark. If there is no mint mark, it indicates the coin was minted in Philadelphia.
The lack of a mint mark indicates that the coin was minted in Philadelphia. The mint mark P wasn't added to quarters until 1980.
This date regardless of mint mark is valued for the silver and is worth about $3.25
If it has one it'll be on the reverse below the eagle. No mint mark = Philadelphia, D = Denver.
The 4 mints producing the 1908 Barber Dime were;(1) Denver which uses the letter "D" for a mint mark, (2) New Orleans which used the letter "O" for a mint mark, (3) San Francisco which uses the letter "S" for a mint mark and (4) Philadelphia which did not place a mint mark on this coin.
The M is not a mint mark but on every coin and is on the right side. The mint mark is to the left od the date slightly above.
If it has one it'll be on the reverse below the eagle. No mint mark = Philadelphia, D = Denver.