This week's crop of new songs features Zac Brown Band teaming with Dolly Parton for an uplifting new track. Meanwhile, Brandi Carlile previews her upcoming album with the new anthem "Returning To ...

A good song becomes a great song when Dolly Parton joins Zac Brown Band's "Butterfly." Seriously though, how often has that been the case? The country legend seems to be amid a collaboration era.