So while stuck at home I tried to find the origin of an old bluesy tune that Jack White did for the American Epic TV show. The tune is Matrimonial Intentions and I found that the original (or oldest recording) is by Buddy Baker. It can be heard here:

The Jack White version can be heard here:

The difference between the two is the JW version has a ragtime break/fiddle tune.

My question is what is that tune?