When I was growing up in postwar Britain, most people had a very narrow view of mushrooms. Even my own family just thought they grew in fields where horses left their poo, and they were white with pink gills that turned dark brown as they got older. We called them "field mushrooms," or "horse mushrooms" if they were bigger.

Actually, those field mushrooms (known as meadow mushrooms in America) were Agaricus campestris, while their larger cousins were A. arvensis. We ate both, but called any other fungi "toadstools" and believed they were dangerous to eat.

Many people make that distinction between "good" mushrooms and "bad" toadstools, though there's no scientific difference between the two — as I learned from Peter Driver, my school biology teacher with whom I went on my first expedition to the Canadian Arctic in 1958.

There, I realized that one of those fungi we'd branded as a toadstool was actually quite delicious. Brown on top with thick stems, and known as penny buns (Boletus edulis; a.k.a. ceps or porcini), they were common in the summer tundra along with white puffballs (Calvatia gigantea), which are also edible when young.

However, it was coming to Japan at the age of 22 that really opened my eyes, and alerted my taste buds, to the wonderfully diverse world of edible wild fungi.

Here, this summer's heat broke records, and it was even sweltering in our Afan Trust woods, 700 meters up in the Nagano Prefecture hills. For three weeks it hardly rained too. Then it started pouring, the temperature dropped and, lo and behold, up sprouted many kinds of mushrooms — some poisonous or just inedible, but several appetizing sorts as well.

The first ones I picked were penny buns, which don't have gills on the underside but small tubes like a sponge, though their flesh is firm and they're good for all kinds of cookery. This year there were plenty to feed lots of guests.

However, my favorite wild fungi are Caesar's mushrooms (Amanita caesarea). If I didn't know they were edible, I would presume they were poisonous like the rest of the Amanita family — most of which, including the psychoactive fly agaric (A. muscaria) and the deadly death cap (A. phalloides) and destroying angel (A. bisporigera), also grow in our woods.

Caesar's amanita first shows itself out of the ground like a white egg, which gives it its Japanese name tamago dake, which means egg mushroom. Very soon, a bright, orange-red head protrudes, growing into an orange parasol on a long stem. It is a delicate fungus and has to be picked fresh and cooked, or dried, as soon as possible.

Usually I use them in a meat sauce, or serve them in miso soup, but my greatest culinary triumph with tamago dake was when I kept drying, vacuum-packing and freezing those I collected until I'd saved up enough to feed all our woodland staff and a few friends.

On that occasion, I steeped them in water until they became soft and the water turned saffron yellow. Then I drained them and cooked spaghetti in the water while I fried the mushrooms with butter, salt, black pepper, various herbs and lots of sea urchin roe. All who ate praised the dish.

It was very different some years ago when I was filming a wildlife documentary on the Kamchatka Peninsula way north of Hokkaido across the Sea of Okhotsk in the Russian Far East.

Out in the woods one day I spotted some of those orange-colored delicacies, which I took back to camp. There, our Russian guide insisted they were poisonous and I would die if I ate them. Though he convinced the Japanese film crew not to touch them, I bet him 100 rubles I'd come to no harm. Then I toasted three over our campfire after he refused to let me use the frying plan, and washed them down with tea, beer and vodka.

When I got up hale and hearty in the morning — and demanding my 100 rubles — our guide just shook his head and refused to pay up. Despite all my protestations, he insisted the bet was off because I must be some kind of shaman as those mushrooms would kill any human being.

The guide probably confused Caesar's amanita with the red, speckled caps of fly agaric. Those can definitely make a person very ill and have hallucinations, though some locals there used them to get high. Not for me, thank you!

What this little Russian recollection does highlight, though, is how difficult it can be to identify wild mushrooms. So anyone thinking of eating any of them must really (really!) know what they're doing, or take the advice of an expert.