Acorn and beech mast

The acorns of oak and nuts of beech that fall in autumn. Their main use was as food for pigs: under the custom of pannage, swineherds drove herds into woods to fatten on them, and Domesday Book often measured woodland by the number of pigs it could support. Pannage was a valued right, and forest law restricted it. People ate acorns only in hard times, as unripe ones are harmful to humans.

Sources: metmuseum.org · wildlifeonline.me.uk