$10. Someone stamped it on the bill after it left the printing office.
Note that this site has a Coins and Currency thread for asking questions about, well, coins and currency. Money and Credit is for things like checks, credit cards, loans, etc.
The issuing bank identifying letter and number is printed on the obverse of all US $1 banknotes. A1 indicates that the note was issued by the Boston Federal Reserve Bank.
Look at the plate number in the upper right corner. There will be a capital letter with a small number to the right of the number. If there is a tiny "FW" on the left of the number the bill was printed in Fort Worth. If not, it was printed in Washington, DC. Ex. A bill might say D12 so you would know it was made in Washington. If it read FWD12 it would be from Fort Worth
A capital letter is defined by being printed in a larger size or different form than its corresponding lowercase letter. Pretty much any letter which is printed in a larger format can be capital letter.
if its does not have a mint stamp it was minted in philly
It's usually enough to just look at the bill's series date and letter (if any) to get an idea of the year or years when it may have been printed. If you want to know a more specific date within that range the Bureau of Engraving and Printing and other sites have tables that can help match a particular serial number / series date combination with the month in which the bill was printed. In general though, the series date and letter are sufficient to determine a bill's value. Please see the Related Question for more information.
brow
Assuming the bill is the same size as modern bills, it was printed in Washington by the Bureau of Engraving and Printing. The letter is most likely some kind of flag or plate indicator.
The Makarel tabby
If the letter G is to the left of Washington's portrait, inside a black ring, then that's the Federal Reserve Seal, and the letter corresponds to a specific Fed bank where the bill was printed. G indicates Chicago.
The issuing bank identifying letter and number is printed on the obverse of all US $1 banknotes. A1 indicates that the note was issued by the Boston Federal Reserve Bank.
If the bill is dated before 1990, it was printed in Washington DC. For later bills, look to the right of the Treasury Seal. In very small print, there will be a letter and number such as D182 or H7, which indicates the plate position of that bill during printing. If there are the letters FW just before it, the bill was printed in Fort Worth. If not, then it was printed in DC.
forebear, Faustian, forehead and many others
L is the Federal Reserve district letter. The series letter is next to the date, and will either be not present, or an A.
There's no 1976-A series of $2 bills. All were printed in the first series which doesn't have a letter next to the date. You may be referring to the Federal Reserve District letter.
forehead
I would have to assume since it is called the Boston News Letter, that it was probably printed in Massachusetts.
More information is needed. If it doesn't have a green seal, what color is printed on it? What date and series letter? What condition is it in? See the link below for more.