Country couple Miranda Lambert and Blake Shelton are teaming up to launch a new music festival in 2015. The two stars will co-headline the inaugural Big Barrel Country Music Festival in Delaware in June. Carrie Underwood, who will be a new mum by then, will also appear alongside more than 45 additional artists, including Jake Owen, Chris Young, Gary Allen, Lynyrd Skynyrd, Loretta Lynn and Merle Haggard.