Also vote heavily worn. MMs from the teens and early 20's seem to have worn away quite quickly in circulation.
My guess is a weak "D", but straight on pictures of the reverse (and less wear) would definitely be helpful.
I'll see if I can get any better pictures of the coin. I was guessing a worn 22-D but after seeing the back I was guessing die #3 with the weak reverse. I still think it might end up in my 1922 Plain slot for my Dansco.
You won't be able to picture this, be see if the back is rotated bout 15°. If so, it is likely die #3.