Tan and white border collie lost in Mansfield

I lost my dog, a tan and white border collie mix, yesterday around 3pm after he slipped out of his blue collar near the Mansfield Public Library on South Street. He's about 40 pounds, with a crescent-shaped white patch on his chest and one floppy left ear. Last seen darting toward Oak Street and the town square by the fountain outside the coffee shop, maybe toward Maple Ave. This dog means a lot to me—he's my emotional support buddy and was a gift from my mom; I’d be so grateful to have him back. He wears a blue collar with a bone-shaped tag that says Milo.