The earliest recordings, before those black-grooved-plastic-thingies, were done on cylinders of wax, tin foil and plastic. While the first media for audio may lack much by today’s standards, there remain many reasons to keep these accessible, if nothing more for the sake of history and education.
Open Culture is a great source for matters regarding what is well described by their name. They featured an article about the University of California-Santa Barbara Cylinder Audio Archive releasing 10,000 cylinder recordings for streaming or downloading. Not only is the collection free, but is also searchable and has a page organized for browsing. The browse page offers both genre and instrument category links.