Townes Van Zandt - Pancho and Lefty
Willy Nelson and Ray Charles - Seven Spanish Angels, [Willie Nelson] Me and Paul, Stardust, Red Headed Stranger
Johnny Cash - Folsom Prison Blues and Ring of Fire
Merle Haggard - Turn Me Loose Set Me Free somewhere in the middle of Montana
Guy Clark - Gotta Get Off This LA Freeway
Hank Snow - The Golden Rocket, I've Been Everywhere
Patsy Montana - Cowboy Sweetheart
Mother Maybell Carter - Wildwood Flower
Gentleman Jim Reeves - Closer to the Phone
Tex Ritter - Hillbilly Heaven, Willie the Wandering Gypsy and Me
Red Foley - Chattanooga Shoe-Shine Boy
Hank Thompson - I didn't know God made Honkytonk Angels
Kitty Wells - It Wasn't God Who Made Honkytonk Angels
Johnny Horton - Honkytonk Man, Miss Marcy
Lonesome Charlie Pride - Is Anybody Going to San Antone or Phoenix Arizona
Edit: Wally's question about Boraxo reminded me - Frankie Laine, Mule Train
Afterthought:
Two of the best country songs of the 20th Century:
Ride 'em by Kinky Friedman [only country song ever written about the holocaust]
Ballad of the Absent Mare by Leonard Cohen