Welcome to the world of wild edibles! Lambsquarter grows all over Iowa, often unwanted, but it’s related to spinach and tastes very similar. If you find it in your backyard, take advantage of those free nutrients (and be sure to wash well first)!
Store lambsquarter in an unsealed bag in the fridge.
Lambsquarter is best raw, or very lightly cooked. Use it in a salad, or add it at the end of cooking a dish for a nutrient boost and spinach flavor.