Marshmallow

Latin name: Althaea officinalis
Plant Family:  Mallow (Malvaceae)
Lifespan: Perennial
Origin: Europe
Growing: They love moist soils and a good amount of sun. In perfect conditions, I had one in my garden reach close to 7 feet tall. It does really well here in the Pacific Northwest and even does decent in a partially shady spot.
Edibility: Like most mallows, the leaves and flowers are edible. The 2 perennial edible mallows that we grow on the farm are marshmallow and checker mallow. Greens are mucilaginous but quite tasty when cooked. 
Medicinal uses: Root is great for soothing inflammations of the mouth and gastrointestinal tract. I harvest the roots in the fall, dry them and save them for tea when a stomach issue or sore throat arrises. 
Permaculture Uses: Can be used as a trellis for vine crops such as groundnet znc can provide shade to plants such as mints and wasabi. Also provides a significant amount of biomass for compost and chicken feed.
Price: $5 for small starts. $7 for larger plant in gallon pot.