A date is needed. Please see the question "What is the value of a (date) US 20 dollar bill?" for more information.
1990
Grover Cleveland appeared on two different $20 bills, both printed in the 1914 series. There's more information at the question "What is the value of a 1914 US 20 dollar Federal Reserve Note?" For clarity, the bill was actually printed in Washington and was distributed by the Richmond Federal Reserve district.
A denomination is needed. Please look for questions in the form "What is the value of a 1928 A US [denomination] dollar Federal Reserve Note?" for specific information.
1928-series $100 bills weren't issued as silver certificates, only gold certificates and Federal Reserve Notes. Please look at the bill's front to determine which you have; then check one of the following: "What is the value of a 1928 US 100 dollar Federal Reserve Note?" "What is the value of a 1928 US 100 dollar gold certificate?"
I don't know but I have one too and I am interested to know.
$22 to $45 depending on condition
$50
There were no series letters on any 1929-dated US bills. A large "G" indicates that the bill was distributed through the Chicago Federal Reserve District. There's more information at the question "What is the value of a 1929 US 5 dollar Federal Reserve Note?"
Probably slightly over face value
"A" is the highest series letter for 1928 $50 Federal Reserve Notes. "K" is most likely the Federal Reserve District letter. The series letter, if any, on US bills is next to the date. Please see the question "What is the value of a 1928 US 50 dollar Federal Reserve Note?" for more information on values.
$100.00
There were no series letters on any 1929 US bills. You may be referring instead to the Federal Reserve District letter; "G" indicates your bill was distributed by the Chicago district. There's more information at the question "What is the value of a 1929 US 100 dollar Federal Reserve Note?"
$12 to $15, assuming average wear.
Grover Cleveland appeared on two different $20 bills, both printed in the 1914 series. There's more information at the question "What is the value of a 1914 US 20 dollar Federal Reserve Note?" For clarity, the bill was actually printed in Washington and was distributed by the Richmond Federal Reserve district.
In worn condition, face value only. If only slightly worn, $8 or so.
That L indicates a Federal Reserve bank branch. The series 2003 $2 bill is worth $2.
Face value for all of them.
As of 09/2008 auction prices are around $24.