The U.S. does not have a "M" mintmark. Look at the coin again and post new question.
If it has a mintmark it's on the reverse just above the letters DO in DOLLAR.
The value of a dollar coin would depend upon the date it was minted, the mint mark and the condition of the coin.
The mint mark (if it has one) on all Morgan (1878-1904 & 1921) silver dollars is on the reverse of the coin, just above the letters "DO" in dollar.
If the coin has any wear the value is for the silver, about $8.50
$23 to $40,000 depending upon the mint mark and the condition of the coin.
If you know it's a 1921 "S" Morgan you found the mint mark
The U.S. does not have a "M" mintmark. Look at the coin again and post new question.
If it has a mintmark it's on the reverse just above the letters DO in DOLLAR.
The value of a dollar coin would depend upon the date it was minted, the mint mark and the condition of the coin.
The mint mark (if it has one) on all Morgan (1878-1904 & 1921) silver dollars is on the reverse of the coin, just above the letters "DO" in dollar.
The date and mint mark are on the edge of the coin, and it's worth one dollar.
In 1921, the US Treasury minted both a Morgan and Peace Silver Dollar. Which type do you possess? Please provide to me the mint mark, mint state, and the type of coin, and I will subsequently relay to you its worth. Also, NO U.S. circulating coin is pure silver. Silver is too soft by itself, and is always alloyed with copper. Silver dollars minted in 1935 and before are 10% copper. it is a Morgan dollar, no mint mark
If the coin has any wear the value is for the silver, about $8.50
A Morgan dollar without a mint mark would have been minted in Philadelphia. The P mint mark wasn't used on $1 coins until 1979. But more information is needed to determine a value. Morgan dollars were minted from 1878 to 1904 and again in 1921 so you need to know the coin's date, plus have an idea of how worn it is. Please post a brand-new question with the coin's date, or enter the question "What is the value of a [date] US silver dollar?" in the box at the top of the page. [date] is of course your coin's specific year.
$2750 to $145,000 depending upon the mint mark and the condition of the coin.
$28 to $35,000 depending upon the mint mark and the condition of the coin.