green card

The work permit from the historical greenish color (first used in 1946), the bank card from its green design, made to resemble US dollar bills.

1USA US work permit, officially known as United States Permanent Resident Card.
2(field hockey) A warning card, given to a player for an infraction of the rules. A further infraction may warrant a yellow card or red card.
3(banking) A chargecard launched by American Express in 1969.
4Used other than figuratively or idiomatically: see green,‎ card.