Some great additions above.
Rhonda Vincent is FANTASTIC! I saw her live at the Coachella Music Festival in 2014, I think it was. She’s a fantastic fiddler and singer, with a real fine band. She has albums going back decades, available for peanuts.
I saw Dolly backed by Alison Krauss and Union Station (I lived two blocks from the NBC studio in Burbank, and walked to the taping), so got to hear not only Dolly sing live, but also Alison and Jerry Douglas (her dobro player, and the father of a kid they made together) from only twenty feet away (I was in the balcony directly above the stage).
Alison’s guitarist/mandolin player/harmony singer Dan Tyminski (he sings "Man Of Constant Sorrow" in O Brother Where Art Thou) has a pair of good solo albums.
Wanda Jackson (mentioned in a post of mine above) has a pair of recent albums that may be of interest to you youngins, as they were produced and recorded by Jack White. He also produced a "comeback" album with Loretta Lynn, which I didn’t care for but you may.
Patty Loveless is right at the line where Country and Bluegrass meet. She has great taste in material, is a real good singer, and surrounds herself with the best musicians. Highly recommended!