A picayune was a Spanish coin, worth half a real. Its name derives from the French picaillon, which is itself from the Provençal picaioun, the name of an unrelated small copper coin from Savoy. By extension, picayune can mean "trivial" or "of little value".
Aside from being used in Spanish territories, the picayune and other Spanish currency was used throughout the colonial United States. Spanish dollars were made legal tender in the U.S. by an act on February 9, 1793. They remained so until demonetization on February 21, 1857. The coin's name first appeared in Florida and Louisiana, where its value was worth approximately six-and-one-fourth cents, and whose name was sometimes used in place of the U.S. nickel.
A newspaper published in New Orleans since the 1830s, the Times-Picayune (originally The Picayune), was named after the coin.
In Truman Capote's 1958 novella Breakfast at Tiffany's, the main character, Holly Golightly, is said to smoke cigarettes with the brand name "Picayunes".