Wild Foods Day
This is a day on which all kinds of clever people can make their "stalking the wild asparagus" jokes.
Some wild life parks who observe Wild Foods Day will observe it sometime around 28th October, either a bit before or after depending on when they can hit a Saturday or Sunday so that people can participate -- they aim for the last Saturday in October.
They offer field trips that later show you how to prepare what you've found.
Remember not to try gathering Wild Foods on your own: go with a certified expert, particularly if any of the food collection involves mushrooms.