Joy Williams and John Paul White, the two halves of saccharine chamber-folk act the Civil Wars, met in Nashville at a songwriting camp. Really? Are we sure they weren’t cooked up in some market-research laboratory? Do people this attractive and stylish really attend songwriting camps? Some things we must take on faith. The duo splits the difference between the rugged bombast of Mumford & Sons and the delicate harmonies of Nickel Creek, and the formula is a hit: This show is sold-out. Best head on over to Craigslist if you want tickets.