Here is the beginning of an illustration of Red Salad Bowl Lettuce:
Here is a bit of the history of lettuce from Wikipedia with a bunch of little fun facts:
The earliest depiction of lettuce is in the carvings at the temple of Senusret I at Karnak, [Senusret I was the second pharoh of the Twelfth Dynasty of Egypt. He ruled from 1971 BC to 1926 BC], where he offers milk to the god Min, to whom the lettuce was sacred. Lettuce was considered an aphrodisiac food in Ancient Egypt, and appears as such in The Contendings of Horus and Seth.
Later, Ancient Greek physicians believed lettuce could act as a
sleep-inducing agent. The Romans cultivated it, and it eventually made
its way to the Papal Court at Avignon, France