Try looking into some Carter Family recordings. They were popular with the "country folk" then. They recorded such popular songs as "Keep On the Sunny Side," "Wildwood Flower," "Oh Bury Me Beneath the Willow," and many more. The Monroe Brothers were also becoming popular in the '30's and recorded such songs as "All the Good Times are Past and Gone," and "Long Journey Home" and many old time mountain & fiddle tunes. These 2 groups represent the foundation upon which Bluegrass was built. Their contributions are beyond measure! How one could overlook them is unimaginable.