Culinary uses for bolted lettuce?
While it might be too tough and bitter to eat as a raw salad, you might try it as a warm wilted lettuce salad with a sweet and sour dressing (bacon, bacon grease, onions, cider vinegar, sugar) to help mask bitterness.

Alternatively you might also try a Lettuce and Pea Soup:
Sweat onions in butter, season with salt and pepper.  Add lettuce and wilt down.  Add fresh or frozen green peas along with chicken stock and bring to a simmer until peas are soft and tender.  Puree (maybe add a little chopped fresh mint) and adjust seasoning with additional salt, pepper, and sugar if the peas don't produce enough sweetness.