The MoonPie hit the markets of Chattanooga Tennessee in 1917 and R.C. Cola arrived in 1934. They were an instant success when they combined forces in the 1950's. You could buy a RC (Royal Crown) Cola and MoonPie special for 10 cents, back then, that was a full 16 ounces of soda and the MoonPies' weighed about near (that's southern for Approximate size) a half pound.
This combo was soon labeled as the instant fast food lunch of the fifties. Although it's never been acknowledged that the merging of the two was a planned marketing strategy or just plain luck.
This combination has inspired many to write, read and celebrate in its existence. Songs about the combo include "RC and Moonpie" sang by NRBQ to "Moonpie" by Edwin Hubbard to a popular childrens musical version by Bill Harley called "Weezie and the Moon Pies". Several books on the subject include "The Great American Moon Pie Handbook" by Ron Dickson in 1985 and the somewhat newer children's book "Jimmy Zangwow's Out-of-This-World Moon Pie Adventure" written by Tony DiTerlizzi and released in 2000.