First Aid Kit -- Fri., noon Last weekend at Rhode Island's Newport Folk Festival, Swedish duo First Aid Kit won over the hearts of thousands, fitting in appropriately beside acts playing traditional American folk and roots tunes. Despite growing up across the Atlantic, Joanna and Klara Söderberg -- two sisters, only 18 and 20 years old -- grew up absorbing US '60s singers like Joan Baez, Buffy Sainte Marie, and Joni Mitchell. Most may remember them for a 2008 video of a Fleet Foxes cover that went viral on YouTube, depicting the girls in a forest, belting out their pristine version of "Tiger Mountain Peasant Song." The success of that video was followed up by a bedroom-recorded LP, and more recently, their gorgeous sophomore album, The Lion's Roar, full of finger-picked acoustic ballads, lush harmonies, and dark lyrics inspired by Swedish folklore. It's no wonder Mike Mogis and Jack White have produced them and Conor Oberst is a frequent collaborator.