OK, I had to find out some more about these two items which I've never heard of before.
I mostly came across recipes for blueberry buckles, but it can best be described as a blueberry coffee cake.
There is lots of information about the slugburger, however, even a Wikipedia article.
The slugburger is a big thing in northeast Mississippi, especially around Corinth (where the Slugburger Festival is held) and Iuka. It started when John Weeks came from Chicago in 1917 and had a hamburger with meat, extended by potato flakes and flour. This really caught on during the Great depression when people were trying to extend their food dollar as much as possible.
Sometime before 1950, these extenders were replaced by soy grits.
At one time it was called the Weeksburger, but the name slugburger became attached to it. In that part of Mississippi, a slug was slang for a nickel, which I imagine is what it cost.
In Tupelo, Mississippi, there was a drive-in called Johnny's, which served slugburgers. As a youth, Elvis ate there.
There is also a Weeks Diner in Booneville, Mississippi.
Next Time Through, I'm Gonna Have to Get Me a Slugburger! --RoadDog