Sorry I didn't give more specific examples in my first post. If I were going to recommend a beginner's library of great country rock, it would have to include the following, specifically:
The International Submarine Band Safe At Home
The Byrds Sweetheart of the Rodeo
The Flying Burrito Brothers The Gilded Palace of Sin
Gram Parsons Grievous Angel
Buck Owens The Buck Owens Collection
The Jayhawks Rainy Day Music, Blue Earth, and Hollywood Town Hall
Rank and File Sundown and Long Gone Dead
The Silos Cuba
Steve Earle Copperhead Road and El Corazon
Rosanne Cash Interiors and Kings Record Shop
Jimmie Dale Gilmore After Awhile and Spinning Around the Sun
Joe Ely Honky Tonk Masquerade
Neil Young Comes A Time
Lucinda Williams Car Wheels on a Gravel Road
Kasey Chambers The Captain
The Old 97s Fight Songs
Jo Carol Pierce Bad Girls Upset By the Truth
Neko Case Blacklisted
The Blasters American Music
Trailer Bride Whine de Lune
Drive-By Truckers Decoration Day
The Bottle Rockets The Brooklyn Side and 24 Hours a Day
Jason and the Scorchers Fervor
Elvis Costello Almost Blue
Gary Allan Tough All Over
Buffalo Springfield Buffalo Springfield Again
These are in no particular order, hardly comprehensive, and lean too heavily on alt-country (sorry, but I could never get much into the Uncle Tupelo/Son Volt/Wilco branch of the tree). Sorry for repeating what's already been mentioned...