August 1, 2009 The US Mint has not issued a quarter with an "M" stamped on it. Probably what you have is a quarter that someone has put their initial on or marked it for some reason. With such a mark it has no numismatic value but is worth $2.52 for the silver it contains.
1¢
How much is 926 worth
25 cents
25 cents
$3.00
$10
it is worth about 50 dollars
Around $6.
1964 was the last year for silver quarters.
The value is only for the silver about $3.25
It's worth around $5.50 for its silver content.
about 134 dollars