No, there is no "M" mintmark for use on US Coins. There was however from 1920-1940 an "M" mintmark for the Manila branch of the US mint, they however made no coins intended for circulation in the US but rather coins for the United States' territories.
In addition, two famous US coins carried an "M" as their designers' monograms: the Morgan dollar, designed by George Morgan, and the Standing Liberty quarter, designed by H. A. MacNeil.
Currently just the Denver and Philadelphia Mints make coins for general circulation.
The US has four mints that make coins. The US mints make coins in the denominations of 1 cent, 5 cents, 10 cents, 25 cents, 50 cents, and 1 dollar for general US circulation. Half dollars and dollar coins are not often used but they are legal tender and can be used in circulation. The US mint also makes bullion coins made of silver and gold. On top of that they make special coins that commemorate anniversaries of special events. These are just some of the coins that the US mints make.
There are currently four active US Mints, not 3: Philadelphia, Denver, San Francisco, and West Point. Philadelphia and Denver are the 2 primary mints, because they make all circulating coins. San Francisco makes proof and some other collectors' coins, while West Point makes platinum, gold and silver coins.
Currently US coins are made at four mints. The Philadelphia and Denver mints make coins for circulation. The San Francisco makes proof coins sold to collectors and investors. The West Point mint makes special coins that are not put in circulation and are sold to the general public.
you can get coins from the mint by ordering the coins through the us mints web site follow this link www.usmint.gov.
Although an independent country, the Republic of Palau uses the US Dollar as its currency. Those coins are minted at the various US Mints. Palau also issues "Republic of Palau" thematic collector coins, also minted at US mints.
Currently, there are 4 operating mints in the US.
1907 in common currency, but the mints use it now for special collectors coins.
Hoover is not on any US coins. He is scheduled for a $1 coin in 2014 as part of the on-going series honoring each president. Many mints have produced medals of the US presidents which resemble coins . Some foreign countries have minted coins with US presidents on them to sell to Americans- one of them may picture Hoover.
In the history of the US there have been 8 mints. Today there are 4 in use.
US Coins go from the Mint to one of 12 Federal Reserve Banks and then to local banks were they are released into circulation.
The first US Mint was located in Philadelphia. It produced its first general-circulation coins (large cents and half cents) in 1793. Philadelphia was the only US Mint until 1838 when branch mints were opened in Charlotte and Dahlonega GA to mint coins from the gold deposits found there. Other mints followed, and today there are 4 active ones. Philadelphia and Denver make circulation coins, San Francisco makes proof coins for collectors, and West Point makes commemorative and bullion investment coins.