This is an image of part of the garden at Lynmar Winery in California. As you can see, in between these beautiful purple chard plants are heads of lettuce. The chard plants are soaking up the sun and the lettuce is happily growing in its shade.
This is a clever example of companion planting with lettuce. Since lettuce doesn’t like a lot of heat, the idea is to plant it so it grows in the shade of larger, sun-hogging plants. That way you can have lettuce in a sunnier location and prolong its growing season. I’m may try this myself this year.