Steven Tyler and Cyndi Lauper are the latest music icons to jump on the country bandwagon, while more and more country stars are taking cues from the pop and rock worlds. (Sturgill Simpson covering Nirvana, anyone?) The mix of albums coming out of Nashville this spring and summer prove just how wide country music's doors are open. We narrow it down to the 10 must-hears, from a Rock and Roll Hall of Famer-gone-country to some steadfast country traditionalists.