Beats me. Crawfish boils?
I feel like it had to be a coonass who first looked at a bug in the ditch and thought "I bet that would taste good with corn and potatoes." But I don't know that for sure. Southeast Texas and even as far as Austin, in small pockets, eat boiled crawfish.
However.
The "crawfish boil" is not just boiled crawfish. It's not a restaurant thing. You do it at home, outside, with at least a dozen of your friends or family, preferably at wooden picnic tables. The crawfish boil is a social event as much as a meal. Everybody brings their own veggies that they want to throw in the pot and let them soak. Host provides the corn cobs and taters, tho. It's polite amongst friends and family to chip in $5-10 for expenses, though certain occasions warrant that the host springs for everything. Water and soft drinks are tolerated. Beer is preferred. Wine is grounds for an ass-beating. You can be all the sommelier you want in other settings; this is not the place for it. If it doesn't last for at least two hours, you did it wrong.
I'm cheating because this is not technically a food, but I don't know what else to put.
There are also some people in TX and MS who do this, but they got it from us.