The Joseph K. Boy World War II Ephemera Collection is a small collection of printed materials collected by Boy during his service in World War II. Boy served with Co. B, 1st Medical Squadron, 1st Cavalry, as a grade T/4 Medical Technician. He served in the Bismarck Archipelago, New Guinea and Luzon, Philippines. He most likely collected the materials during his time in those locations.

The collection includes ten examples of Japanese invasion money, paper bills printed by the Japanese government in 1942 as part of their attempt to establish control over the Philippines. Denominations represented in the collection are: one centavo, ten centavos, five pesos, ten pesos (two different examples), and 100 pesos.

Thirteen pieces of small printed propaganda in the collection were presumably printed by the Japanese to encourage American soldiers to surrender, as they convey anti-U.S. military sentiments. For example, one flyer depicts the island of New Guinea with a dead soldier lying across it, holding a military order signed by General MacArthur; the poster's text appeals to soldiers' fear of being killed and places blame on the U.S. military leadership. Another shows a lady representing death embracing a U.S. soldier and suggests that surrendering is the only way to avoid death. Three small pieces, each with different illustrations, are "Tickets to Armistice" that provide instructions to U.S. soldiers on how to surrender to the Japanese Army Headquarters.

At the end of the collection is one 30x42-inch color poster depicting a Lockheed P-38 Lightning and a Grumman F4F-3 Wildcat. The poster was produced as an aide for Japanese pilots to be able to identify American aircraft.