lettuce, and red onions. There are plenty of foods you should always buy at Costco, the pre-made Bacon Cheddar Burger meal kit isn't one of them. At first glance, the patties don't look appetizing.

For the easiest bit of meal planning, you should turn to Costco's tasty variety of read-to-eat meals for a bit of help.

And though ingredients and toppings vary widely from one salad to another, the base ingredient they all have in common is some form of lettuce. Here's which types of lettuce are most popular ...