Imagine a time when everyday Americans couldn’t find enough coins for a loaf of bread or a newspaper. During the Civil War, the nation faced a severe shortage of small change—silver and gold coins were hoarded for their metal value, which exceeded their face value amid rampant inflation and distrust in paper money. To keep commerce moving, the U.S. Treasury improvised with something unexpected: tiny paper notes worth fractions of a dollar. Among these “shinplasters” (as they were nicknamed for their resemblance to bandages), one stands out as the rarest and most intriguing—the 15-cent fractional currency note. Issued only between…