I recommend some of the old country material from the '20s and '30s that was recorded on 78 rpms. Bands like Gid Tanner and the Skillet Lickers and the North Carolina Ramblers and Uncle Dave Macon. Here's a must: Fiddlin' John Carson playing "The Farmer is the Man Who Feeds Them All."
The County and Rounder record labels include compilations of these artists.
For something more recent, try the Clinch Mountain Boys "The Fields Have Turned Brown."