During World War II the U.S. used $1 bills that were stamped with the word "Hawaii" on them. Could you explain a little about them and maybe something about their value today?
We found an answer to your question at the Web site of the Federal Reserve Bank of San Francisco.
Not only were $1 bills stamped, but $5, $10, and $20 San Francisco Reserve notes also featured the brown seal and serial numbers that the Bureau calls the "Hawaii overprint." This was done in July 1942 to keep Hawaii's paper money isolated from the rest of the U.S. in case Japan invaded Hawaii. This way the Japanese could not use the money to their advantage. It wasn't until Oct. 21, 1944 that normal monetary conditions were returned to the region.
Here's what the U.S. Dept. of the Treasury's Bureau of Engraving and Printing says about how much the bills are worth:
This is what we suggest as well. But we do have some good news. All of the online sources we checked said that, depending on their condition, these bills are indeed worth more than their face value.
—The Fact Monster