Sugarland
Sugarland, an American country music duo, is composed of singer–songwriters Jennifer Nettles (lead vocals) and Kristian Bush (background vocals, lead vocals, mandolin, acoustic guitar, and harmonica). Sugarland was founded in 2002 by Kristen Hall with Bush and ultimately became a trio after hiring Jennifer Nettles as lead singer. After three years, Hall left the group.
source: Wikipedia