Here's where it started - we were walking the perimeter of the playing field and couldn't help noticing a large number of conspicuous dark green rings on the grass - clearly of fungal origin...

A closer inspection revealed lots of little white mushrooms lurking amongst the grass along each of the rings.

They were quite difficult to see at all, until we were right on top of them.

I picked one - and was delighted to discover that the mushrooms in this field really were field mushrooms.

I didn't have my basket to hand, but I always carry a few clean plastic bags folded up in my wallet - not exactly ideal for gathering mushrooms, but good enough just to get them home.

What Are Field Mushrooms?

Agaricus campestris - Similar in overall appearance to the common white mushrooms commonly sold in shops - although a little more fragile.

Familiarity

Such familiarity could give rise to complacency, but even here, there is every bit as much reason to be cautious and to seek a positive and reliable identification before eating the mushrooms. There are a couple of similar species that, although not deadly poisonous, are deeply unpleasant in either flavour or their effect on the human digestive system.

Identifying And Picking Field Mushrooms

They vary in size between tiny, round, closed cap buttons to taller, flat or concave-capped specimens, 10cm across or more.

The gills are baby pink in small unopened mushrooms (the gills are never white, even at this stage), changing to deep chocolate brown (almost black) in older ones.

The smell is pleasantly 'mushroomy' and the flesh may turn pinkish when bruised or cut.

Many sources expressly state that there should be no trace of yellow on this species (see comments below on the 'yellow stainer') - and this threw me for a while, as some of mine did have pale yellow centres to the caps, and some subtle yellowing at the base of the stalks.

Roger Phillips' excellent and authoritative book Mushrooms and other fungi of Great Britain and Europe, however, confirms exactly what I found - not conspicuous bright yellow staining - that would be a bad sign - just a bit of pale yellow on some of the caps and stalk bases, sometimes.

I picked a nice big heap of the mushrooms - trying where possible to break off the base of the stems before placing them in the bag, to prevent earth and sand from being shaken into the spaces between the gills.

Back home, they required minimal cleaning - just a bit of trimming and a few blades of grass to brush off

Cooking

Agaricus species are really good just fried in a little butter and served on toast - when cooked, they release juices that are almost meaty in their intensity of flavour.

But we already had some baked spuds in the oven, so the fried mushrooms went on top of these, with a little bit of grated mature cheddar to finish.

We still had plenty left the next day, so I fried off some little bits of bacon, adding the mushrooms in near the end, then packed this into blind-baked shortcrust pastry shells, poured over a beaten egg and added some cheese.

Baked in a medium oven for about twenty minutes, these were delicious.

The Genus Agaricus

Field mushrooms are closely related to the familiar white mushrooms sold in shops, and also to other well-known edible species such as horse mushrooms and wood mushrooms.

However, every family has its bothersome relative and this is no exception. The Yellow Stainer mushroom - Agaricus xanthodermus is similar in appearance to the field mushroom, but is not safe to eat - causing severe stomach cramps and sweating in some people.

It is easily distinguished from the field mushroom by two obvious criteria (as well as a number of more subtle ones):

The flesh turns bright yellow within seconds or minutes of being cut or bruised and the whole thing has an unpleasant chemical smell described as 'inky'.

Location?

People can get a bit precious about their mushroom-picking spots, and the locals probably wouldn't thank me for starting an internet - fuelled mushroom rush, so I'm afraid I'm not going to reveal the location I picked these - but if you keep your eyes peeled, you might be lucky and find some of your own.

Keep an eye out for those dark green grass rings - in some cases, you can even spot them using Google Maps.