Chinese Artichoke

Latin name: Stachys affinis
Plant Family:  Mint (Lamiaceae)
Lifespan: Perennial
Origin: China
Growing: They are cold hardy but require a good amount of water to get good production from the tubers. They can grow both in partial shade and full sun, although my most productive ones are in partial shade. Once established, they take care of themselves and are a generally reliable crop Overall it does really well in the Pacific Northwest.
Edibility: One of my personal favorite perennial edibles in our gardens. I harvest the small tubers from fall all the way through winter to eat both raw and as an addition to stir fries. They are low in calories, high in iron, and produce large yields. Large yields are great in this case since the tubers themselves are usually less than an inch long.
Permaculture Uses: Not only is it a perennial vegetable, but also a reliable ground cover to shade out weeds and keep moisture in the soil.. 
Price: $5 per plant.