Sam Bayard's field recordings from the mid-1900s in Pennsylvania are now available on YouTube. This was noted on the Banjo-L list, and I've been listening it for a while this morning. It exists as a youtube playlist, where the video is an image of the typewritten notes associated with the field recordings. It's organized by artist/source.
News item on the digitized collection: http://news.psu.edu/story/303628/2014/02/11/music/bayard-old-time-music-tunes-available-youtube
YouTube Playlist: https://www.youtube.com/playlist?list=PLfkrWr_vIGB9l33oOjTC2M6JlhxfoPlQz