12 Rated Stampless Folded Letter

Here's a 12 rated stampless, folded letter dated 1843 from Frederick,
MD to a lawyer in what I take to be Hagerstown. It openly states "cash"
in the second line of the address and is also marked 1 enclosure.

The letter is folded so that it is double the thickness of a single sheet
and is emobssed with the mark of what I take to be the paper manufacturer,
J. Ames.

So was a $20 note so openly enclosed or did the envelope contain a
check for the $19.94 mentioned inside? The last name on the signature
looks like "Cash."

The Frederick, Maryland stamp is in green. A previous owner paid $40
for this cover.