If you are looking for collections that contain many of the above-mentioned recordings, there is the excellent 'White Country Blues' referred to above. Others that are worth seeking out include:

'Old-Time Mountain Blues' County CO-CD-3528
'Hillbilly Blues 1928-1946' Fremeaux & Associes FA 065 [double CD set]
'Prayers from Hell: White Gospel & Sinners Blues 1927-1940' Trikont US-0267
'Mountain Blues: Blues, Ballads & String Bands 1927-1938' JSP7740 [4-CD set]
'Worried Blues' JSP7743 [4-CD set that has complete output of Frank Hutchison and Kelly Harrell                                                                                                                                                      
et alia].

Tony Russell's seminal Studio Vista booklet 'Blacks, Whites and Blues' has been reissued with others essays from the same press in 'Yonder Come the Blues' Cambridge Uni Press

Lawrence Cohn's 'Nothing But the Blues' Abbeville Press includes an excellent essay by Charles Wolfe: 'A Lighter Shade of Blue: White Country Blues'.

--Stewie.