Thanks, Phil. That digitization of the WPA tape is just what I was looking for! It was a lot harder to struggle with the reel-to-reel tape at the LoC!

That said, the LoC notes did label several of those items as launching songs.

And the first rendition of John B strikes me as potentially notable in how different it is from how one might imagine a 1900s-composed pop song to be performed.

Not sure what you mean by "serious" work song.