Datura stramonium
Datura stramonium, also called  Jimson Weed, Gypsum Weed, Stink Weed, Loco Weed, Jamestown Weed, Thorn Apple, Angel's Trumpet, Devil's Trumpet, Devil's Snare, Mad Hatter, Crazy Tea, Malpitte, Beelzebub's Twinkie and Zombie's Cucumber is a common weed in the Nightshade Family.  It contains tropane alkaloids that are sometimes used as a hallucinogen.  The active ingredients are atropine, hyoscyamine and scopolamine which are classified as  deliriants, or anticholinergics. Due to extremely high risk of overdose, many deaths and hospitalizations are reported from recreational use.
Datura stramonium also called dhatura is an erect annual plant, on average 30 to 150 cm (1-5 feet) tall with erect, forking and purple stems.  The leaves are large, 7 to 20 cm (3-8 in) long and have irregular teeth similar to those of oak leaves.  The flowers are one of the most distinctive characteristics of Datura stramonium: they are trumpet-shaped, white to purple, and 2-7 in. (5-12.5 cm) long. The flowers open and close at irregular intervals during the evening, earning the plant the nickname Moonflower.  The fruit are walnut-sized, egg-shaped, and covered in prickles, they split into four chambers, each with a few kidney-shaped seeds.  All parts of the plant emit a foul odor when crushed or bruised.

# Cultivation and Uses
Jimson weed grows in most habitats, but thrives in high-nutrient soil. It is found throughout much of the United States, most commonly in the South. Datura stramonium is also found throughout many other parts of the world. Goats will occasionally eat jimsonweed, and subsequently die a slow and painful death. In California and other western states, Datura wrightii is found, not Datura stramonium. It is common in the west, known as
Gypsum weed. Gene Autry noted it his song "Back in the saddle again"
"Out where a friend is a friend
Where the longhorn cattle feed
On the lowly gypsum weed
Back in the saddle again"
Datura is occasionally used as an available alternative to illegal drugs. Typically it is not illegal, although some American states do have laws regulating its consumption. It is typically consumed as a sort of herb tea, though it can also be eaten or smoked. Overall, it has a very low demand as a recreational drug, because it has a reputation as a very poor/unpleasant high, as well as being potentially fatal.

# Effects
There is a mnemonic device for the physiological effects of datura/atropine intoxication: "blind as a bat, mad as a hatter, red as a beet, hot as hell, dry as a bone, the bowel and bladder lose their tone, and the heart runs alone." Another rhyme describing its effects is, "Can't see, can't spit, can't pee, can't shit."  Regarding Datura, among the Navajo is the folk admonition, 'Eat a little, and go to sleep. Eat some more, and have a dream. Eat some more, and don't wake up.' The actual effects are reported to be: cycloplegia and mydriasis (extreme dilation of the pupil), flushed, warm and dry skin, dry mouth, urinary retention and ileus (slowing or stopping of intestinal movement), rapid heart beat, hypertension or hypotension, and choreoathetosis/jerky movements.  In case of overdose the effects are hyperthermia, coma, respiratory arrest, and seizures.  The vast majority of atropine-poisoning cases are accompanied by delirium with visual and auditory hallucinations.
The effects of Datura have been described as a living dream: consciousness falls in and out, people who don't exist or are miles away are conversed with, etc. The effects can last for days. Tropane alkaloids are some of the few substances which cause true hallucinations which cannot be distinguished from reality. It may be described as a "real" trance when a user under the effect can be awake but completely disconnected from his immediate environment. In this case, the user would ignore most stimuli and respond to unreal ones.  This is unlike psilocybin or LSD, which only cause sensory distortions.
The doses that cause noticeable effects, and the doses that can kill are very close with datura.  This makes overdosing on Datura stramonium very easy. This can be fatal; it can cause fevers in the 105-110 (40-43C) range which is a range that can kill brain cells, and lead to brain damage.  There have been many instances of teenagers looking for a cheap high poisoning themselves to death on datura. If someone overdoses on datura it is advised to induce vomiting, to wash out his or her stomach, and to get the person hospitalized immediately.
If taken recreationally and the user does not notice any conscious effects, most people redose thinking it's not working, which is why overdoses are so common. The user doesn't realize that he or she was hallucinating.  Some users have reported seeing an array of people from their lives.  A few anecdotal reports also mention the user's perception of "phantom cigarettes"; the person believes that he or she is smoking a cigarette only to find that it has disappeared later, thus realizing that it never existed. At the peak of such experiences users often enter a true psychotomimetic state, in which they "lose touch with reality" altogether; at this point, many find it difficult or impossible to communicate with others.
A majority of users who have written reports on experiences with this drug have described those experiences as unpleasant and often terrifying. This is possibly due to their having taken excessive doses. The powerful effects of Datura continue until the body metabolizes the tropane alkaloids.
Scopolamine is the primary hallucinogen in Datura wrightii from California and other Daturas.  Scopolamine can be slowly and erratically absorbed into the brain.  In most people, scopolamine reaches the brain within an hour or so after ingestion and causes visual and auditory hallucinations.  In about 25% of people, scopolamine is very slowly absorbed into the brain, taking up to 13 hours to enter the brain.  These are the people who are at the highest risk of overdosing.  They become impatient waiting for their recreational high and take more of the plant extract.

# History
Datura stramonium is native to either India or Central America. It was used as a mystical sacrament in both possible places of origin.  The Native Americans have used this plant in sacred ceremonies.  In some tribes datura was involved in the ceremonies of manhood.  The sadhus of Hinduism also used datura as a spiritual tool, smoking it with cannabis in their traditional chillums.
In the United States it is called Jimson weed, Gypsum weed, Angel Trumpet, Hells Bells or more rarely Jamestown Weed; it got this name from the town of Jamestown, Virginia, where British soldiers were secretly or accidentally drugged  with it, while attempting to suppress Bacon's Rebellion. They spent several days chasing feathers, making monkey faces, generally acting like lunatics, and indeed failed at their mission:
Some of the soldiers sent thither to quell the rebellion of Bacon (1676); and some of them ate plentifully of it, the effect of which was a very pleasant comedy, for they turned natural fools upon it for several days: one would blow up a feather in the air; another would dart straws at it with much fury; and another, stark naked, was sitting up in a corner like a monkey, grinning and making mows  at them; a fourth would fondly kiss and paw his companions, and sneer in their faces with a countenance more antic than any in a Dutch droll.In this frantic condition they were confined, lest they should, in their folly, destroy themselves- though it was observed that all their actions were full of innocence and good nature. Indeed, they were not very cleanly; for they would have wallowed in their own excrements, if they had not been prevented. A thousand such simple tricks they played, and after 11 days returned themselves again, not remembering anything that had passed.
 Robert Beverly, The History and Present State of Virginia, 1705
There was a time when stramonium, a drug obtained from the leaves and seeds of Datura stramonium, was used medicinally (Herbalgram). The alkaloid was known as daturine. From the seeds was made extractum stramonii. The tinctura stramonii was made from the leaves.  Stramonium was used to relax the smooth muscle of the bronchial tubes, and thus it was used to treat an asthmatic's bronchial spasm. Cigarettes were made of stramonium leaves which could be smoked; or the tincture was taken internally. Frequently the leaves were powdered together with equal quantities of the leaves of Cannabis and Lobelia mixed with potassium nitrate, and were burned in an open dish. The preparation was reported to give off dense fumes which afforded great relief to the asthmatic paroxysm. Around the turn of the century numerous patent "cures" for asthma contained these ingredients in varying proportions. Daturine was also used to treat acute mania as hyoscyamine was said to produce sleep. Because of the dangers of tropane poisoning, datura is not used medicinally today, and the Food and Drug Administration (FDA) has determined it to be unfit for human consumption.  However, atropine, scopolamine and hyoscyamine are FDA approved drugs that are used everyday for a variety of conditions.
The antidote of choice for overdose or poisoning is physostigmine.