"... one of the puzzles of history..."

It's been too long since I have done a reading from the Holy Scriptures, Tree Crops, A Permanent Agriculture by J. Russell Smith.

From the chapter entitled "The Oak as a Forage Crop" (and quoting at a length that I'm sure exceeds "fair use," a consideration which I - and I'm sure the brilliant J Russell would agree - is superseded by the benefit of committing these words to pixels and spreading them across the ether):

The genus of oak trees hold possibility, one might almost say promise, of being one of the greatest of all food and forage producers in the lands of the frost.  Why has it not already become a great crop?  that is one of the puzzles of history, in view of its remarkable qualities...

... As the pioneer farmers of Pennsylvania pushed aside the flowing stream of oil from their springs so that animals might drink water, so the modern world has pushed aside this good food plant, the oak tree.

There is a strip of hills from New England to Minnesota, from New England to Alabama, from Alabama to Ohio, from Ohio to Missouri, and from Missouri down to Texas.  On these hills men have been making their living by growing wheat, corn, clover and grass.  Yet I am confident that in every county there are oak trees of such productivity that if made into orchards they would in any decade yield more food for beast and possibly man than has been obtained on the average in any county in any similar period on the hill country of this wide region.

Word first written in 1929.
I often focus on acorns as a human food - and rightly so given the fact that humankind has eaten more acorns than all grain crops combined. 
However, given the fact that most soil-killing and fossil fuel-consuming grain crops are grown to feed livestock (whether the animals' digestive systems evolved to eat grains or not), the idea of using acorns as a forage crop takes on new poignancy.