There's plenty of early/proto country music on Harry Smith's magisterial "Anthology of American Folk Music". I 'd have said that any modern country music with roots very clearly in this sort of music is almost certainly American Folk Music. It's all about "rootedness in tradition" for want of a better turn of phrase, and I think one of the difficulties about some modern country music is that it has moved so far away from its roots they are barely, if at all, discernable*. I guess there has to be a point at which music that can be traced back to folk music becomes something else in its own right.

Having said that, in our information heavy age, it's quite possible for a contemporary musician to bypass the last 70 years of country music history and end up sounding like this.

* Which is not, of course, necessarily a judgement on quality.