Start with Dwight Yoakam. He is a strong an artist playing traditional country in so many of it's subgenres as you can find. And, he rocks harder than most "rock" bands. Then get the first Flying Burrito Brothers album, as well as both Gram Parsons albums. I'd also suggest the Long Ryders, Native Sons, and Steve Earle's output up to Transcendental Blues. That should be enough to transition into the classic country...Johnny Cash, Hank Williams Sr., George Jones, Buck Owens, Lefty Frizzell, Waylon Jennings and Ray Price. Bobby Bare is very good, too. And, look for anything written by Harlan Howard, one of the great country songwriters. And, if you want to here what real country pop sounds like, you could do a lot worse than checking Glen Campbell...great voice, one of the great session guitar players in the 60's, and he put out four absolutely classic singles - Gentle on My Mind, By the Time I Get to Phoenix, Wichita Lineman and Galveston. (The last three of which were written by Jimmy Webb.) And, you cannot do wrong checking out Patsy Cline.