There is a flock of Canada geese where I live. Yesterday they were feeding along the street and also in the street. I drove right up to them and watched them eat white oak acorns as fast as they could. They mouthed the acorns to seperate the caps and husks and ate the center while expelling the rest. They skipped the largest acorns for the medium and small ones. The acorns that had fallen onto asphalt were the easiest to seperate.

Any goose hunters ever observe this among wild flocks?

Never saw a Goose eat one, however all the puddle ducks love them. Mallards, Gadwalls, Woodduck's etc.