Dandelions

Yarrow

Wild mushrooms

Elderberries

Lamb's-quarters

Plantain

Burdock

Wild grapes

Nettles

Catnip

Black walnuts

Wild rice (permit required from Minnesota DNR)

Picking tips: "Pick plants as if you're in the produce section. Look for fresh, healthy and happy specimens," said Minneapolis herbalist Lise Wolff. Harvest conservatively, leaving plenty of leftovers for wildlife and other foragers (and for yourself, perhaps in future seasons).