No. You cannot freeze lettuce. If you were to freeze lettuce it would appear to be fine and intact. However, as soon as you were to attempt to thaw the lettuce it would start to get soggy and mushy.
You certainly CAN freeze lettuce, but you probably don't WANT to. Lettuce is 90% water, so freezing it makes the vegetable cells burst. When it thaws, it's totally limp.