“Sorry, your stamp is not what you think it is. It’s not that special.” Workers at the Philatelic Foundation in Manhattan often say such things when shown an unusual postage stamp, but this time foundation curator Lewis Kaufman wasn’t so sure. A recent cellphone photo of an “Inverted Jenny”—the 1918 stamp with an upside-down plane printed only 100 times—looked surprisingly real, the New York Times reports. Kaufman told his boss, Larry Lyons, who called back an Illinois man who said his family had stored the stamp in safety deposit boxes for generations. Amazingly, it would be only one of two Inverted Jennies still unaccounted for since financial clerk William Robey spotted the misprint during his lunch hour on May 14, 1918, per the Smithsonian.
Planning to buy a stamp celebrating the new US airmail service—which used the Curtiss JN-4 or “Jenny” to deliver mail—Robey realized his luck and bought the entire 100-stamp sheet for $24. After telling friends and collectors, Robey fell under scrutiny and sold the sheet for $15,000 to a Philadelphia businessman who then resold for a profit. The stamps were then numbered on the back and resold, sparking an occasional legend (Robey may have spent his windfall on a car that he drove through a wall) and a theft (four were stolen during a stamp convention in 1955). Knowing all this, Lyons flew to an Illinois bank to see the stamp numbered “49” on the back. “I had a big magnifying glass with me, and the colors were so fresh,” says Lyons of the stamp that could be worth over $1 million. “And then I turned it over and saw the 49 and went ‘Jackpot.'”