I would suggest going to the bank. You can purchase these coins there. If they don't have any go to the nearest coin shop and see if they have what you want.
M is the monogram of George Morgan, the coin's designer - hence, Morgan dollar ! You need to look on the back for a mint mark. See Related Questions for more specific information.
The M is Hermon MacNeil's initial the man that designed the coin.
The U.S. does not have a "M" mintmark. Look at the coin again and post new question.
The "M" you see on the ribbon that ties wreath together, stands for Morgan, as in George T. Morgan the designer of the coin. Also another "M" is on the base of Miss Liberty's neck on the front of the coin.
The mint mark on an 1848 US dollar coin can be found on the reverse side of the coin, below the eagle and above the "M" in the word "DOLLAR." If the coin was minted in Philadelphia, there will be no mint mark present, as the Philadelphia Mint did not use mint marks until 1979.
The coin has 40% silver in it or .3161oz of pure silver.
The coin is a Morgan dollar the "M" is the designers George T. Morgan initial and 1921 is the highest mintage year of the series, values for circulated coins are low at $16.00-$20.00
The "M" is the initial of George T. Morgan who designed the coin, it's found on the neck and the left-hand loop of the ribbon on the reverse.
The mint mark, if present, is located on the coin's reverse, in the triangular area between the word ONE and the tips of the eagle's tail feathers. No m/m = Philadelphia D m/m = Denver S m/m = San Francisco
Continued: I heard that if there is a M on the front of the coin it is a morgan which there is no M then i heard it would be considered a peace silver dollar but when i looked at the picture of a piece silver dollar the pictures were different.
Ellen M. Finley has written: 'Notes on the history of Fillmore, California' -- subject(s): History
If you have a U.S coin, M is probably the monogram of the designer. I can think of at least 2 such coins, the Morgan dollar designed by (drum roll, please) Morgan, and the standing liberty quarter designed by MacNeil.