In Season: Available year round Lettuce is said to have been around for more than 2000 years. Interestingly enough, the Emperor Caesar Augustus believed that lettuce cured him of an illness and built a statue in its honor. The second most popular fresh vegetable in the United States, lettuce can be found in several different varieties, each used for an assortment of dishes. In a pinch, lettuce can be surprisingly handy. During the shortages of WWII, Russians used lettuce latex as a rubber substitute.