Thanks Howie
It appears that the local oaks are going to put out a bounty this year, so I will have to set a day aside and do some foraging.
Many years ago, I did just that - collected acorns, shelled them at home and tried boiling the tannin out to make them edible. Unfortunately (and I didn't know this at the time), when changing the water, you have to add them from boiling water
to boiling water; going from hot to cold will lock in the remaining tannin and the nuts will be permanently bitter. That's what happened the last time.
This is probably also suitable for the Kitchen forum, since acorns have been used for flour as well.