Roadside Cornucopeia

Why are some plants considered weeds when they are both edible and medicinal? There are many plants that grow on the side of the road or that we pluck out in gardens, which were seen as food or in some instances sacred medicine by indigenous people. It would be interesting to see what factors have shaped our disregard for some of these plants today. I initially thought of the dandelion, which most folks tend to value just for their aesthetics. Where as this plant actually has multiple use-values. I like the idea of exploring urban and rural foraging as a sustainable practice.