Here's a paragraph from one of Alan's archived pages:
Recently, I spoke with a friend who told me his uncle was in the screenprinting business in the mid-to-late 1930s. One of the items he screenprinted for companies (filling stations, Cracker Jack, and small local businesses in the area of western Pennsylvania) and individuals (i.e. political campaigners) included marbles. This elderly gentleman, Howard E. Koehler, was born in 1910, and obtained his marbles from Akro Agate. Over the years he has given these marbles to his relatives, including his nephew, my friend, who showed me a jar full. Among the marbles were Popeyes, Corkscrews, and Opaques. Many were printed with the names of individuals, while others had the names of petroleum companies (Esso, Mobilgas, and Sunoco) and such words as "freedom" and "1937." Mr. Koehler himself kept around 100 of these marbles, and allowed me to go through them. Perhaps some of the more interesting examples contained "Landon" or "Landon/Knox"; Alfred Landon and Frank Knox were the repulican candidates for president and vice president, respectively, during the 1936 election, and lost against Franklin D. Roosevelt.
Another link, with more detail from Alan: http://dir.groups.yahoo.com/group/dixiemarblecollectorsclub/message/981
Guess I should save that page in case it disappears or is hard to find for some reason.