The government once accepted postage stamps as payment
During the Civil War, there was a shortage in the supply of coins — people were holding onto them because the precious metals were valuable, according to the Bureau of Engraving and Printing. To address this, the government accepted postage stamps as payment for debts.
Ironically, and perhaps unsurprisingly, this caused a shortage of stamps. So, the government authorized printing “fractional currency,” which were bills with denominations under $1.