The Boston Celtics have reached agreement with Dallas Mavericks free-agent guard Jason Terry on a three-year contract, league sources told Yahoo! Sports.

The Celtics will use their $5 million mid-level exception to sign Terry. The total value of the contract will be worth more than $15 million.

Terry spoke with Celtics president Danny Ainge and coach Doc Rivers on the first day of free agency Sunday. Rivers told Yahoo! Sports he hopes Boston can still re-sign Ray Allen, in addition to adding Terry. The Celtics have also already reached agreement with Kevin Garnett on a three-year, $34 million contract.

via Marc J. Spears of Yahoo! Sports