Good condition: $50 - $100
Very good condition: $100 - $200
Fine condition: $200 - $300
Very fine condition: $300 - $400
Extremely fine condition: $400 - $500
Uncirculated condition: $500 - $1000+
The M mint mark indicates that the coin was minted in Philadelphia. Morgan dollars minted in Philadelphia are generally more common than those minted in other mints, such as Denver or San Francisco. However, the 1921 Morgan dollar with an M mint mark is still considered a desirable coin by many collectors.
If you have a 1921 Morgan dollar with an M mint mark, it's worth getting it professionally appraised to determine its exact value. An expert coin dealer or numismatist can assess the coin's condition, rarity, and other factors to provide you with an accurate estimate of its worth.