Start with the easy species — and a rule you never break

A British wood in spring is a larder, if you know what you are looking at. But foraging has one absolute rule that overrides everything else: never eat anything unless you are completely certain of its identification. Not fairly sure. Not "it looks like the picture in the book". Certain. If there is any doubt at all, leave it, enjoy looking at it, and walk on.

That is why the sensible approach is to start with the small handful of species that are genuinely easy to identify — wild garlic, sorrel, nettles and a few others — and to learn them properly before you branch out. Use a good field guide, one with clear photographs or drawings of the whole plant, including leaves, stem, flower and root. Take it with you rather than relying on memory, and check your find against two sources if you can. Certainty is the whole game.

Wild garlic: the confidence-builder

Wild garlic, also called ramsons, is the best plant to learn first. It grows in damp, shaded woodland, often in enormous carpets along streams, in old deciduous woods and along hedge bottoms, and it is at its best from March to May.

The leaves are broad, soft, pointed ovals, usually two to a stem, growing from the base of the plant. The flowers are star-shaped and white, carried in loose clusters on a triangular stem, and they appear a little later, in April and May. Here is the test that settles it: crush a leaf between your fingers. It should give an unmistakable fresh garlic aroma that lingers on your hands. If it does not smell of garlic, it is not wild garlic.

• Where to look: damp shade, bluebell woods, stream sides, the bottoms of hedgerows.
• How to use it: leaves raw in salads, shredded into pesto, wilted into soup or folded through mashed potato. The flowers are edible too and look lovely scattered over a dish.
• The confusers: lily of the valley, bluebell leaves and young lords-and-ladies all share that broad green leaf shape, and all are toxic to some degree. None of them smell of garlic. Smell every leaf, every time.

Wood sorrel and other sharp little leaves

Wood sorrel is the next one to learn. Look for it in the shade of old trees, on mossy banks and around tree roots, often in the same woods as wild garlic. Each leaf is made up of three heart-shaped leaflets, a little like a small clover, and they fold down at night and in the rain. The taste is clean, sharp and lemony.

A few leaves are a lovely addition to a salad, but wood sorrel contains oxalic acid, so treat it as a garnish rather than a vegetable. Keep portions small, and avoid it altogether if you have gout, kidney stones or a sensitive stomach. Common sorrel, with its arrow-shaped leaves, grows in grassland and at woodland edges and gives much the same lemony tang.

Nettles, elderflower and brambles: the seasonal staples

Stinging nettles are everywhere and underrated. Pick the top four to six leaves of young plants in spring, before they flower — gloves on, and nothing low down where dogs walk. Blanch them for a minute and the sting is gone, leaving a spinach-like green that makes a fine soup or a homely pesto. Nettles that have flowered and set seed are gritty and tough, so leave them.

Elderflower arrives in late May and June, in flat, creamy-white heads with a honeyed scent. Pick when the tiny buds are just opening, shake them gently to dislodge insects, and use only the flowers; the stems, leaves and roots are best avoided. Elderberries follow in autumn and must always be cooked.

Brambles give you blackberries in August and September. Pick fruit that is fully black and comes away from the stem with a gentle pull, and leave the red ones to ripen. A crumble is reason enough to spend an afternoon in the woods.

The lookalikes that actually matter

Most foraging accidents come down to a handful of plants, so learn these properly and you will be far safer.

• Broad-leaved umbellifers: cow parsley, hogweed and their relatives grow in the same kind of places, and hemlock water dropwort — one of the most poisonous plants in Britain — grows by streams and ditches. Unless you can identify an umbellifer with total confidence, do not eat it.
• Giant hogweed: its sap causes serious burns when skin is exposed to sunlight, and it is common on riverbanks and verges. Learn its jagged leaves and thick, blotchy stems and keep well away.
• White flower heads: elderflower is fairly distinctive once you check the whole shrub, but other white umbels are not. Always look at the leaves and stems, not just the flowers.

Forage legally, gently and sensibly

In the UK, picking wild flowers, foliage, fruit or fungi for your own use is not theft under the Theft Act 1968, but digging up a plant without the landowner's permission is an offence. Rules differ on nature reserves, Sites of Special Scientific Interest and land with its own byelaws, so check before you fill a basket. Never pick a protected species, and never strip a patch bare: take a little from many places and leave plenty for wildlife and for next year.

A few practical habits worth keeping: avoid roadside verges and any land that may have been sprayed, wash everything at home, try a very small amount the first time you eat a new species, and keep a note of what you ate and where you found it.

Start with one plant per season. Learn wild garlic this spring until you can spot it from twenty paces, then add sorrel, then nettles. That is how the knowledge sticks — and how you will always be certain enough to eat.