QuinoaAn easy to grow and generous plant can be kept quite happy in a raised bed, which does make it easy to harvest. The only down side is that because you are growing the plant for it's seed (to grind up) it can look less than attractive for the last few weeks.
Chick
PeasChick Peas are also easy to grow and lovely in the garden.
If you pick the peas for flour, you can continue to pick and dry the peas as they are produced, and the plant will continue to give you more.
Wild
YamDioscorea is a well mannered climber that can be harvested every Autumn or left until the following one if you have enough.
It will self sow the next crop if you raise the first but you can also keep them in the ground until you need them.
Yam
BeanJicama is very easy to grow, and the tuber that it produces is delicious and nutritious. The tuber is the only edible part of the plant with the seeds or beans being quite toxic.