Iris Dement (Merle loved her, recording her "No Time To Cry"), Patty Loveless, Emmylou, Rosie Flores, Jann Browne, Mary Chapin Carpenter, Carlene Carter (June Carter’s daughter), Kasey Chambers (good Australian singer), Randy Travis, Lyle Lovett, Steve Earle, Jim Lauderdale, Vince Gill, Albert Lee (guitarist in Emmylou’s band for years, also played for The Everly Brothers), Steve Wariner, Joe Nichols, Jerry Douglas (the greatest living dobro player, in Alison Krauss’ band), Rodney Crowell (one time member of Emmylou’s band), Marty Stuart (his band The Fabulous Superlatives are imo the best band in the world at the moment), David Ball (great true Honky Tonk singer), Buddy Miller (Emmylou’s longtime guitarist/bandleader/harmony singer, also a great solo artist and producer), Ricky Skaggs (on the Bluegrass side of Country as of late), Doug Seegers (a true Hillbilly, with the twang to prove it), Asleep At The Wheel (Western Swing), The Del McCoury Band (as Hillbilly as it gets. Start with the album they did with Steve Earle---it won’t sound so "foreign"), dozens of others, but that’s a start ;-) .
Unfortunately, the greats from the 1950’s, 60’s, and 70’s---Hank Williams, Hank Thompson, Lefty Frizzell, The Louvin Brothers, Webb Pierce, Bob Wills (Merle Haggard’s favorite musical artist---he recorded a tribute album to the man), Ray Price, Merle of course, Buck Owens (Dwight Yoakam’s stylistic model), George Jones, Tammy Wynette, Loretta Lynn---were recorded in indifferent sound quality, not what I think you’re looking for. That, plus it was really, really Country, if you get my drift. Way more Hillbilly than you younger fellas can stomach.
But if you want some great pedal steel guitar, you gotta get a Speedy West collection. He was THE player in the 50’s/60’s, and is who all the young players study. Acoustic guitar, steel guitar, fiddles, and harmony singing is now heard in Bluegrass music, not what is being called Country. That is, mainstream Country. Americana is where real Country made by "artistic" practitioners (rather than mere entertainers) is heard (many of them listed above). Head over to the No Depression website to read all about it.
