Toby Keith and Dierks Bentley are among the acts releasing greatest hits albums Tuesday (May 6). Keith's 35 Biggest Hits, a two-CD set, covers his career from his 1993 debut single, "Should've Been a Cowboy," through his current hit, "She's a Hottie." The collection is being released as a joint venture of Show Dog Nashville (which Keith owns) and Universal Music Enterprises. Bentley's Greatest Hits/Every Mile a Memory 2003-2008 (Capitol Nashville) features 10 hits, two new songs and five live recordings selected by his fans. Another greatest hits package, the 18-song The Very Best of Confederate Railroad, was also released Tuesday. ... Also new in stores this week is Blake Shelton's Pure BS Deluxe Edition, an expanded version of his most recent album, which contains two new tracks and his current hit single, "Home." Other new releases include 16-year-old mandolin prodigy Sierra Hull's Secrets (Rounder) and singer-songwriter Jason Matthews' Hicotine (S&S Mack).