I have only had it a little East of Memphis, Tn. in Henderson. (I posted here: http://www.chowhound.com/topics/487124 , trying to find the name of the place!)
In the Smithsonian Folklife Cookbook, publish around '91 a recipe for it is listed in the "South/Cajun & Creole" section. The recipe credit is to Chuck Hauer, Memphis, Tn., Tn. Program, 1986. A quick skimming of the forward to that section mentions Germans arrived prior to Acadians & contributed sausages & brown mustard to the cuisine. Hope this helps as a starting point!