A Hawaii overprint note is one of a series of banknotes issued during World War II as an emergency issue after the attack on Pearl Harbor. The intent of the overprints was to easily distinguish United States dollars captured by the Imperial Japanese Armed Forces in the event of an invasion of Hawaii and render the notes worthless. Although a sizeable number of the notes were recalled and destroyed after the end of World War II, many escaped destruction and exist as collectibles of numismatic interest in the present day.

Silver certificates are a type of representative money issued between 1878 and 1964 in the United States as part of its circulation of paper currency. They were produced in response to silver agitation by citizens who were angered by the Fourth Coinage Act, which had effectively placed the United States on a gold standard. The certificates were initially redeemable for their face value of silver dollar coins and later in raw silver bullion. Since 1968 they have been redeemable only in Federal Reserve Notes and are thus obsolete, but still valid legal tender at their face value and thus are still an accepted form of currency.