United States dollar bill signed on the reverse by Cassius Clay (Muhammad Ali). PSA has encapsulated the bill and certified the signature as "Authentic." Clay's signature has been scripted in blue ink and grades 8/10 overall. While a dollar bill might seem an odd item to have signed, it's actually not. Many times when people encounter celebrities in the course of their normal lives, they don't have anything with them that can be autographed. When that happens, the easiest thing is to reach in one's wallet and pull out a dollar bill. That was most likely the scenario that occasioned this bill to be signed in the early 1960s, when Clay was fast becoming a national sports figure. Clay changed his name to Muhammad Ali shortly after winning the heavyweight championship from Sonny Liston on February 25, 1964. The dollar bill (Series A 1963) has "94" written in blue ink and the number "3" written in pencil, both on the front (meaning unknown) and is in Very Good condition overall.