Among the pale, slender trunks of the beeches, Alex Schwab makes the find that — even to such a seasoned hunter of mushrooms — provides a thrill unlike any other.

“Over here,” he commands. I can hear the urgency in his voice and hasten down the slope. “Can you see it?” he asks triumphantly. I scan the ground, focusing on the patches of old, brown leaves between the clumps of bluebell leaves. I know what I’m looking for, but I still can’t see it. Then I do.

It rises perhaps three inches from the forest floor. The top is light chestnut in colour, rounded, slightly irregular. The stalk is plump, creamy, swelling out as it descends. The profile is unmistakable. It is known by different names in many countries, but revered in all. It is the monarch of mushrooms: Boletus edulis, the cep, the penny bun.

“Where you find one there are usually more,” Alex said. Sure enough, there were another three hiding among the leaves: two bigger and much chewed by slugs, beetles and other lowly connoisseurs, but still salvageable; the last a perfect miniature, its cap pushing shyly up through the humus.

It wasn’t a great haul, but enough to save the foray from failure. There are times — rare and transcendent — when you stumble upon the cep in abundance. Two years ago I came upon a crop high above Coniston Water in the Lake District: a great feast in mushroom form, shining like treasure in the damp grass beside the path.

But the cep, like most mushrooms, rejoices in rain as well as warmth. It likes the ground properly moist, and when I went out with Alex into Mortimer Forest, a couple of miles from the Shropshire town of Ludlow, the leaves and sticks crackled dryly beneath our boots.

Alex comes from Switzerland, where the mushroom-gathering culture is much more deeply ingrained. A keen angler like me, his mycological enthusiasm developed in boyhood as he wandered rivers and lakes. In Switzerland every district has its official mushroom inspector, paid to sort the worthily edible from the indifferent, the indigestible and the lethal. In the mushroom world, complicated by an astounding legion of varieties, you soon learn.

Book business brought Alex to Ludlow. One day, walking the nearby woods with Merlin Unwin, his publisher, and Merlin’s family, Alex was explaining the differences between the good fungus, the nasty and the plain bad. Then Karen Unwin had the obvious idea. Why not a book?

There are many mushroom books and most of them are marvellous in their way. But the general approach is to include the inedible and the poisonous along with the good. In Mushrooming Without Fear, Alex has adopted a different method. He covers only the good, and not many of them: 12 varieties in all (cep, red cracked bolete, dotted stemmed bolete, larch bolete, bay, birch bolete, chanterelle, trumpet chanterelle, hedgehog fungus, puffballs, horn of plenty and cauliflower mushroom).

Each is illustrated with his own photographs, and the identifications are accompanied by Alex’s rules, which is where a touch of controversy creeps into this peaceful, rural pursuit.

He tells you always to cook them (for one thing, you can never know what creature has been doing what around or on them); never to pick mushrooms that look, smell or feel rotten; and always to be sure of your identification.

All this is unexceptionable. But then there is Rule 1: Never take a mushroom with gills. And here it gets tricky.

The reasoning is sound. Within the gilled group are found virtually all of the seriously life-threatening mushrooms, most notoriously Amanita phalloides, the death cap, responsible for four fifths of all mushroom-related fatalities. Exclude the gills and you make it safe, goes the theory. And that’s fine, except that you thereby also deprive yourself of the field mushroom, which — when you can still find it — is the delight of our meadows: creamy-white on top, coral-pink beneath, to my palate as fine as the cep itself. You have to make your choice.

Out in the forest I watched Alex at work. He moves steadily, purposefully, low to the ground, zig-zagging through the trees. It takes time, mushrooming, and unflagging concentration, otherwise you miss them. Actually, you miss them anyway: I was accused, possibly unfairly, of walking straight past the ceps that redeemed the day. “You are looking for something that’s not quite right,” is the only tip that Alex gave. I know that sometimes you can smell them before you see them.

I found some red-cracked bolete, lowly cousin to the cep, which are acceptable when very fresh, which these weren’t. We found plenty of false chanterelles, distinctly orange compared with the buttery yellow chanterelle proper (which, being ridged rather than gilled, are on Alex’s approved list). Then, on the edge of a stand of conifers, three fresh field mushrooms shone bright against the needles. I stopped to cut them. “No, Tom,” Alex commanded. “No gilled mushrooms.” Shamefaced, I obeyed.

That evening we ate the ceps, sliced quite thinly and fried in butter. The flesh was pale, smooth and firm, the flavour — of nuts, of trees, of woodland, of late summer verging on autumn — delicate but insistent. I’d forgotten how good they can be. And, Lord, these were good! So do yourself a favour: get some of the knowledge, and get out among the trees. Now is the time.

Mushrooming Without Fear by Alexander Schwab (Merlin Unwin, £14.99)

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