Well I just spent a couple of weeks living in the mountains of appalachia(specifically in asheville, NC). I lived in a tent by a stream and went out almost every night to rounds of musicians playing "old time" music (Old time is a sort of description of any mountain music that is "pre-bluegrass"). Some of the rounds were at houses(these were the best), others were in music shops or bars (where musicians got free beer all night long!!). I mostly observed, but finally got the nerve to play...even played an original "mountain music style" song I wrote. The old guys loved it.
"Old time music" has NO solos, and the fiddle plays the melody the ENTIRE time...but you can improvise in how you play the melody. The fiddle and the claw hammer banjo lead most of the songs. I found out the sub-style I was most interested in is called "modal old time" which is that haunting, bluesy fiddle that I always associated with mountain fiddle music.
The really old guys weren't as uptight as the younger guys (or the imported yankee intellectuals) about keeping it pure...the old guys would even play some of the songs bluegrass and country western style, while their wives clogged or played with their grandchildren, who were always running around. There was tons of food. Great, nice, genuine people. I really took a liking to the really old dudes and their accents. Some of them had never left the mountain(I can understand why). I bought 3 jugs of moonshine from one of them!