The Foragers Digest blog has a fantastic springtime post about wild edible plants. These days their culinary uses are almost forgotten and we classify them as weeds.
But a lot of those "weeds" were carried into the west by pioneer and settler families to be cultivated for food.
Lamb's Quarter is a great example of a long forgotten salad green that is often growing right under our noses.
I weeded Lamb's Quarter out of my garden hundreds of times before I realized what it was.