Rub the inside of a large bowl with the garlic. Add the garlic to the bowl along with the tomatoes and herbs. Season with salt and let stand at room temperature for 1 hour. Discard any large garlic pieces.
Preheat a grill to medium-high. Thread the scallops on skewers and brush with the olive oil; season with salt and pepper. Grill, turning once, until firm and slightly charred, about 8 minutes. Remove from the skewers and add to the tomato mixture.
Add the butter to the scallops mixture and gently toss until melted. Serve with the lemon wedges.