Fred McCullen.
Member of the 1919 "Black Sox" team. Has only one baseball card, a 1916 Zeenut card.
Without coupon, it's a $4k card, give or take. With the coupon, worth even more.
Definitely crosses into the pre-war territory, but it takes the noise out of the equation of:
*Players whose card is only valuable because of someone else on the card.
*Players whose card is only valuable because of a third-party grade of the card (i.e. PSA 10 Gem Mint)
*Players whose card is only valuable because it is part of a really rare, esoteric set (i.e. 1955 Felin's Franks John Meyer)
