Hilary Duff, "Tattoo" (2015)
Ed Sheeran can be a hard guy to pin down. "He had been doing a promo day in L.A. and he's like, 'I know you have a 2-year-old, but could you please come and record at midnight?,'" Hilary Duff told MTV News. The new mom made the time, knowing that this energetic but gently folkish Sheeran track, about the unseen marks that love leave was a perfect fit for her first album since 2007. Sheeran, who handled vocal production on the cut, accompanied Duff in the vocal booth while she sang. "I was really intimidated because, normally, they don't do that," she said. "So I kept looking up and being like, 'You're Ed Sheeran and I'm singing the song that you wrote and I want to do right by it.'" According to an impressed Duff, Sheeran then added backing vocals in 15 minutes.