[Leon]

Not sure if stamps are considered cards, probably not. They are collectibles nonetheless. Here is a stamp of him when he was a governor. He was a governor from December 10, 1935 – October 9, 1939. He started as Baseball Commissioner in 1945. OldCardboard has his 1949 Eureka Stamp as his first appearance. So this predates that one but it's before he joined baseball..