Stinging Nettles, Urtica dioica

One of the main reasons for nettles being imported and grown in Britain was for producing fibres.
Nettles grow easily in our damp climate and they don't need to be protected from straying livestock or people. They also don't have to be retted (left in a pond to go rotten and very smelly), unlike crops such as flax.
The fibre is in the nettle skins, so can be removed by dragging the plants repeatedly over a board full of close-set spikes.
When making coarser twine or rope, rather than fibre for cloth, the skins can just be peeled off by hand and immediately twisted into position.

You can eat them, as greens, in soup, and in salad after soaking to remove the stinging chemical. The plants should be cropped young, when they have reached a height of six inches to a foot.
Older plants rapidly become woody and have a lot of tannin in them. Mature plants develop oily seeds, these are theoretically nutritious and can be cooked like Fat Hen, Chenopodium album, but are an acquired taste to say the least.
The exception to using young leaves are the mature ones used to wrap Cornish Yarg cheese to give it extra flavour. Try some if you get the chance.

Nettles make an excellent beer and a tolerable tea. Although ladies of my acquaintance say it's the other way round.
As when using them as a food, the young plants are the best for both tea and beer. They quickly become bitter as they mature.

Tea requires an ounce of fresh leaf to a pint of boiling water. Leave them brewing until the water turns green and then remove the leaves. It's tends to come out rather blacker in colour than you expect but that's normal. Add sugar if you must, honey is better.

For beer, you will need about two pounds of nettles to a gallon of water. Boil them up for about twenty minutes, then strain them off and add half a pound of sugar. When it cools to room temperature, add some yeast. You can put in other flavourings such as ginger or cloves if you like them.
Leave it covered in a warm place for about three days and you should have a drinkable brew.
Make sure you use strong bottles if you intend to bottle it and let it mature, it has a tendency to make them explode.
The beer is quite pale in colour but you can get a darker brew by using brown sugar or even molasses.

A new one on me, I saw this a re-enactors fair,
being sold by the Trolls Bottom Bar.

I haven't tried it, yet, but if it's anything like their other wines it will be good stuff.

IMPORTANT. I am not a doctor. I am not a medical herbalist. I do not have any medical qualifications at all.
I am a re-enactor who has an interest in medicine and who plays the role of a Physician. If you are ill, go and see a doctor. A real one. One who has completed a medical degree and who has MD after their name.

I have used nettles on myself and others to good effect. As far as I am aware they are safe to use as described and they are after all edible.
BUT. If you choose to use them, that is your decision and your responsibility. If your leg turns green and runny and then drops off, that is your problem. Don't blame me for it.

The Romans claimed that they relieved the pain of arthritis and a study at the University of Plymouth appears to confirm this have a look at this BBC report.
The juice has antiseptic properties and with a little honey makes a good treatment for a sore throat.
Used as a wound herb, the juice is astringent and will help stop bleeding.
To extract juice for the above, use a handful of mature, dark green leaves, but not ones that have been attacked by insects. Wash them and chop then up. Then add about a tablespoonful of water and crush them in a mortar. Strain of the juice and use within 24 hours.

Nicholas Culpepper 1653
The roots or leaves boiled, or the juice of either of them, or both made into an electuary with honey and sugar, is a safe and sure medicine to open the pipes and passages of the lungs, which is the cause of wheezing and shortness of breath, and helps to expectorate tough phlegm, as also to raise the imposthumed pleurisy; and spend it by spitting; the same helps the swelling of the almonds of the throat, the mouth and throat being gargled therewith. The juice is also effectual to settle the palate of the mouth in its place, and to heal and temper the inflammations and soreness of the mouth and throat.

How about.
You can write with them, ink from the juice, pens from the woody stems. Use the older nettles for this, the darkest green leaves are the best. The juice can be extracted using a pestle and mortar, adding just a few drops of water to a a dozen large dark leaves. An old woody stem can be trimmed into a dip pen by carefully peeling off the skin and then shaping the nib as if it were a goose quill.

You can dye your clothes with them. You know, the ones that were made from the nettle fibre.
The leaves give shades of green, while the roots produce yellow when boiled with alum.

You can make a liquid, though rather smelly, fertilizer. Remember the bit about making fibres when I said they don't need to be rotted in a pond. Well, if you do rot them in a pond, or more likely a bucket., after about a month you'll get a dark and smelly liquid.
Dilute it until it's a pale brown, about a pint to gallon should do, and water your plants with it.

So enjoy your nettles, no need to weed that rough patch at the bottom of your garden. It's a crop now.