Question: Which much more famous artist co-writes and sings backing vocals on Kellie Pickler's 2008 song "Best Days of Your Life"?
Sentence (from "Kellie Pickler (album)"): Since the albums' release, three more singles have charted; "Best Days of Your Life" at number 9 (which was co-wrote with fellow country artist Taylor Swift), "Didn't You Know How Much I Loved You" at number 14 (a re-recording of an album cut from Pickler's debut album "Small Town Girl") and "Makin' Me Fall in Love Again" at number 30.
Relevant evidence: Yes