`Whatever you have heard, all plants are edible'

Did you know that gorse flowers make a delicious addition to green salad and that ground acorn is a stimulating substitute for coffee?

For most of us, contact with food from the wild is limited to the annual autumn walk to pick blackberries. Everything else is regarded with suspicion, used only by Shakespearean witches brewing up poisonous potions. Yet we happily fill our bodies with caffeine, salt and alcohol on the grounds that if it comes from a shop it must be OK.

"Whatever you may have heard, all plants are edible," began Gordon Rutter, a fungus expert at Edinburgh's botanical gardens, at the start of a "food for free" day in Epping Forest. "But some of them you'll only eat once, and you'll never eat anything again."

Of course, poisoning is a risk, but not if you know what you're eating - and it usually takes the form of mild stomachache rather than instant death. "Never eat anything unless you're 100 per cent sure what it is," said Gordon, "and always keep a small amount in a box in the fridge, so that when you're rushed to hospital..." To rub the point in, the course was sponsored by a local hospital, Holly House, presumably in anticipation of extra custom.

Fortunately help is at hand. The "food for free" movement was inspired by a book of the same name by Richard Mabey, with pictures of berries, nuts and leaves and recipes for everything from sloe gin to stinging-nettle haggis. Fancy a Sunday lunch with a difference? How about bilberry Yorkshire puddings, or samphire hash with wild raspberry vinegar?

I could still hear the drone of the M25 traffic as we set off into the forest in search of snacks. First stop was an oak tree, to suck young leaves; then a nearby elder, whose flowers make a refreshing summer sweet. Stalks and leaves of wild garlic were followed by bunches of pungent water pepper, growing on disturbed earth beside a footpath.

When we got on to mushrooms, Gordon was in his element. He found Jew's Ear, a fungus which grows on elder trees, said to have been first formed by blood dropping from the ears of Judas after he hanged himself. "Soak them in water then fry for at least 20 minutes," Gordon advised.

As we picked fat oyster mushrooms from the bark of dead beeches, Gordon told us about fly agaric, the original magic mushroom. They're red with white spots, straight out of a children's storybook. "They're not really poisonous," said Gordon. "Two people tried to commit suicide with fly agaric and all they got was a terrible hangover."

An escaped prisoner once lived wild in Epping Forest for three months, surviving on rabbits as well as leaves. Even vegetarians can create a feast. We returned with baskets full and watched as Gordon rustled up a splendid afternoon tea - infusions of rose bay willow herb and pine needles, elderflower fritters, oyster mushrooms with wild garlic. He showed us how to light a fire in the wild and create candles out of rushes.

A few words of warning before you try it for yourself. Don't touch any endangered species - they have as much right to be there as you do. By law you need the landowner's permission, even to pick blackberries - though in the memorable words of one council official, "We don't mind a small amount for personal consumption."

Remember - if in doubt, don't eat it. And although anything with red and white spots may not kill you, you'll still feel pretty sick.

Epping Forest Field Centre, High Beach, Loughton, Essex (0181 508 7714). The next Food for Free day is in 1996. Gordon Rutter will lead "Fungus Forays" on 7 and 8 October 1995, pounds 18 with lunch. "Food for Free" by Richard Mabey (Collins, pounds 7.99).