Mountain Grass Unit (L-R): Josiah Nelson, Sam Wilson, Drury Anderson, Luke Black. Mountain Grass Unit today releases “Suspicion,” a haunting, traditional bluegrass heartbreak ballad from its forthcoming debut studio album, Appalachian Smoke, arriving August 28 via Dualtone Records. Here, Mountain Grass Unit narrows the frame and lets the lyrics, tension, and unresolved ache do the work. On August 26, Mountain Grass Unit will make its Grand Ole Opry debut following a surprise invitation delivered onstage at DelFest by Del McCoury and Ronnie McCoury. Another Sunday AgainAbout Mountain Grass UnitMountain Grass Unit stands at the intersection of bluegrass music’s past and future.