'In origin, picayune is probably a borrowing from Louisiana French, the rich mixture of French dialects spoken in Louisiana from the beginning of French settlement there in the 17th century and still spoken there today. In the Louisiana French of the past, the word picaillon referred to another small coin, the Spanish half-real, that circulated in the area during colonial times. The word picaillon is in turn a borrowing of Provençal picaioun, a copper coin of Piedmont and Savoy, historical regions of the southeast of France. (Provençal, spoken in the south of France, is a Romance language closely related to French.) Provençal picaioun is ultimately derived from Old Provençal piquar, "to jingle, clink."'
—More Word Histories and Mysteries, from the editors of American Heritage Dictionaries, Boston: Houghton Mifflin, 2006