The traditional symbol of 25 years of togetherness is silver, but for Old Crow Medicine Show, it’s more than an anniversary, it’s a “jubilee.” That’s the title of their new album, announced today, marking two and a half decades as a band that started out busking and now headlines some of the biggest festivals in roots music. Jubilee, coming Aug. 25 on ATO Records, features the newest lineup of OCMS, still fronted by Ketch Secor, as well as guests Sierra Ferrell, Mavis Staples, and OCMS founding member Willie Watson, who left the band in 2011.