The 24¢ Curtiss Jenny biplane is one of the most widely-talked about postage stamps in the world. It was made forever famous when a single sheet of 100 was discovered in 1918 with the blue airplane inverted. This "Upside Down Airplane" has recently been speculated to have been seen on an absentee ballot in Florida. While an inverted error is worth 6-figures one can own this regular airmail for much less!
