Agree - and don’t forget that chickens not only love the greens, but they enhance egg production and quality.. (According to my SO, who keeps the little beasts... ;))
I have seriously considered dedicating my entire garden to turnips, if I were faced with a ‘survival gardening’ situation...
Don’t forget radishes too - grow fast, and the leaves and roots are both good.
Dandelions - I eat them all the time as they taste good, and the roots are wonderful for helping digestion and reducing fever, as well as helping out your liver.
Throw in a couple of rows of shallots and you are good to go.