Good King Henry (Blitum bonus-henricus), also called Poor-man’s Asparagus, Perennial Goosefoot or Markery, is a species of goosefoot native to Europe. Grown as a vegetable in cottage gardens for hundreds of years, its leaves can be used as spinach, and its flowering shoots resemble sprouting broccoli or asparagus.
Good King Henry 
Shoots and leaves are edible.
Growth and habit: a perennial plant that continuously produces foliage and flowering shoots from a clumping root from spring through late autumn, dying down and dormant through winter. Propagation is by a slow spread as a clumping plant; it may also self-seed if the winter is cold enough. Can be carefully dug up and divided every few years.
Harvest: young leaves and shoots, a few at a time, late spring to mid-autumn. Do not over-harvest. Larger outer leaves can be slightly bitter, so leave those on the plant to help it regenerate.
Uses: mild, slightly nutty spinach flavour; use leaves as you would spinach, e.g. raw in salads or wilted/steamed. Shoots can be cooked like wild asparagus or sprouting broccoli.
Further reading:
- Wikipedia: Good King Henry
- Crawford, M. Creating a Forest Garden. Green Books, 2010. (library)