A number of patents mention Labor Day, most of these relate to calendars or calendar-based games.
U.S. Patent No. D34888 on a Design for Medal celebrates the laborer.
U.S. Patent No. 2,284,256 covers on a Card Game features a Labor Day Card.
U.S. Patent No. 3,565,437 on a Discount Store Board Game Apparatus, features a Labor Day sale card (68).