I have an interesting 3CD set, produced by the Country Music Foundation and issued by Warners some time ago now: 'From Where I Stand: The Black Experience in Country Music'. No 'blackgrass', but a useful overview. Surprisingly for such projects, I find that it is still available [the price is much more than I paid - I must have bought it in a sale]. Full details are available here: CLICK.

--Stewie.