Jimsonweed is part of the Solanaceae family, which also includes various potato, tomato, pepper, eggplant and tobacco.
Atropa belladonna (deadly nightshade), which is native to Europe, contains the psychoactive alkaloids atropine, scopolamine, and hyoscyamine.
The Daturas are a closely related cousin to Atropa belladonna. Datura stramonium, which im assuming you were, (thornapple, jimsonweed) is a mostly eastern species and was probably introduced to the Americas from the West Indies.
While these related plants wered used in ceramonial purposes many years ago, they are all highly toxic, and easy to ingest too much. Datura has ALSO been used traditionally by the Mapuche-Huilliche and the Jívaro tribes of South America as a last-resort punishment for unruly children.
The active chemicals are alkaloids. The tropanes include, primarily, atropine and scopolamine. They are
antimuscarinics, which means they block acetylcholine receptors of the
muscarinic subtype (the other subtype, nicotinic, is not affected by
tropanes). There is some evidence that scopolamine is more psychoactive,
possibly because it crosses the blood-brain barrier more readily.
When used at higher than normal doses, tropanes produce some rather extreme
psychoactive effects -- disorientation, confusion, hallucinations, delusions,
panic, etc. The interesting thing about this class of hallucinogens is
that the person taking the drug is often absolutely convinced that the
hallucinations/delusions are, in every sense, real; furthermore, he or she
may attempt to interact with them (and perceive normal response). This
can range from amusing to dangerous. There is often a severe distortion
of position/kinetic sense leading many to say they feel like they were
in free-fall or flying.
The really dangerous thing about tropanes is that they have rather strong
peripheral effects in comparison to their psychoactive effects. The
lethal dose / effective dose ratio is dangerously low; furthermore, the
strength of tropanes in wild plants ranges considerably. The Datura
genus may contain alkaloids which have neurotoxic effects, in addition to
the tropane alkaloids.
Anyways... make your own choices
most of this came from
http://www.erowid.org/plants/datura