All this talk about storage issues ...... and we seem to have not discussed this specific coin.

You can read the history here:
http://www.coincommunity.com/commem...f_dollar.aspSome interesting tid-bits about the 1921 Missouri ....
Daniel Boone appears on the obverse of this coin ...... and later is featured on the obverse of the 1934-1938 Boone Bicentennial Half Dollar ....... this is one of four occasions where one person appears on two Classic US Commemorative.
fyi ..... the other three are:
General Robert E Lee: 1925 Stone Mountain and 1937 Battle of Antietam
George Washington: 1900 Lafayette Dollar and 1926 Sesquicentennial
Booker T Washington: BTW Half and Washington-Carver Half
Your 2*4 example is a great lesson in the greed of the time ..... the 'special designation' signified Missouri status as the 24th State ...... and was really just another way to collect money from the Numismatic world.
Alabama soon followed suit with their 1921 2*2 example (I see you have one posted) ..... for the same reasons ..... greed ... and in 1922 the Grant Half Dollars used a * for the same reason ...... these are the 3 examples in the 144-coin series where the only design change was the addition of a trivial feature intended to force collectors to purchase more coins to keep their collections intact.
There is some ambiguity about the mintage totals for the 1921 Missouri Plain and 2*2 .....
It is accepted that the original mintage of 50,028 coins were struck in Philadelphia in July 1921 ..... and that 29,600 were returned for melting leaving a net surviving 20,428 coins for us to enjoy today.
There are various accounts of how many Plain versus 2*4 were minted however. Some experts claim that your coin New Mismatist has a mintage of 5,000 ...... where other experts peg the number closer to 9,000. Either way ..... this is a low mintage coin.

Interesting to note relative to your fine example that the 2*4 were minted first ..... and that most of them were sold to collectors and thus reasonably well preserved. They also have the best potential for full-strikes.
The deepest recess of this very high relief design is on the reverse of the coin (you have your photos correct this time

) where the leather strap connects the powder horn to the shoulder of the frontiersman. Your coin apprears to be well struck with full details.
You have a real beauty here New Mismatist ...... a very well struck coin that might grade MS-65.
I see a bag hit below Boone's ear on the obverse ...... and some assorted bag hits on the lower half of the figures on the reverse ..... but the fields are clean and well preserved.
Only possible concern was your grandmothers storage ...... Boone's cheek is the high point of the obverse design and your excellent photo shows a bright spot there.
Look under a 10X loupe ...... is that rub where material has been removed?
If so ..... alas .... this lovely is an AU-58 slider.
If this were my coin I would send it to PCGS or NCG for authentication and grading ...... if MS-65 then the Numismedia FMV is $3340.

David
Take a look at my other hobby ...
http://www.jk-dk.art