Potatoes are a good bet- they provide essentially everything you need except Vitamin A. Might be problematic to store in a BOB though, as they will start to sprout on their own.
Potatoes are my favorite, and I eat a lot of them now. They are Extremely Productive for a
given area, But they are Vulnerable to a variety of Diseases. I am not just talking about the
Irish Potato Famine, but more recent crop failures in Europe in the WW II era. Also, I
saw a 1 hour special on public TV and they are always on the verge of crop failure.
Potato farmers are very watchful and are ready with chemicals.
Pro:
root crop, efficient to grow, everyone likes them, people with intestinal problems
sometimes need a bland starchy vegetable. A large variety may limit total crop failure.
Con:
subject to total crop failure, cannot use real seed (see below).
A guy on the internet collects real seed for two reasons 1) he wants to re-establish viability
of real seed 2)he wants more variety for more disease resistant strains.
(Planting potatoes or pieces thereof is just cloning: no diversity (= disease will kill all).