The 22-year-old country sweetheart, who was earlier linked to various people including John Mayer, Zac Efron and Joe Jonas, was spotted enjoying lunch with Foster on May 17 and they tried to avoid being caught on camera by leaving the Los Angeles eatery separately, reported Daily Mail.
Foster, 28, found fame with their song 'Pumped up Kicks' in 2010 and earned two Grammy nominations last year.
He was also recently romantically linked to former 'Buffy The Vampire Slayer' star Michelle Trachtenberg.