Hi Toddy, sorry been on the drink since I posted, so essentially food for human consumption or the by product could be consumed such as berries etc!
Leafs to harvest above would be good, seeds, harder to harvest but maize probably ok!
Small bushes, trees that will mature also ok!
Lost of good ideas already!
What about quick growing, but easily removed trees and shrubs as they get bigger......silver birch, elder, buddleia (though once that's there, it's there

pretty though and the wildlife loves it....the birch is useful and grows really quickly, it's a pioneer species, but the elder will give flourish and berries, as would sloes. Hazel would be nice but squirrels

I'm presuming you don't want brambles, but cherries would be good, and on dwarf stock they're easy to pick. Apples, pears, plums... and underplant with flax and ....you know what would grow a decent mix ? Buy a couple of the big bags of bird seed and just scatter that....ours has sunflowers, wheat, oats, peas, linseed, buckwheat, etc., in the mix. If the birds miss any, up it sprouts.
For leaves, chard, beets, sorrel, the goosefoots like Good King Henry.
I think it really depends on your land and aspect though.