There is one other very special woman I believe everyone should hear---Iris Dement. I learned of her from Merle Haggard, who was raving about her at the time of her 1st or 2nd album, about twenty years ago. Her music is that great blend of singer/songwriter, hard country, bluegrass, and a little folk (not too much!). She not only has a great voice, she is also an astounding songwriter. Merle recorded her "No Time To Cry", but hers is the one to have, on her "My Life" album. Mostly acoustic, she has all the first call Nashville musicians on her records, guys like Jerry Douglas (Alison Krauss band) on dobro. For the atheists out there, let me warn you that she comes from a spiritual place (sounds Southern Baptist to me)---but then so do Buddy and Julie Miller (Julie has a couple of OOP Christian albums out there). As a bonus, her records, like many bluegrass albums, have pretty darn good sound.