A quick search of
Amazon pulls up a ton of books on medicinal herbal remedies. I have one buried in my storage somewhere, but can't recall the name of it just now. I know there was a set of books done based on the "Grow your own Drugs" TV series as well that might be useful to you.
As for poisonous plants, many times I have seen herbal books include poisonous plants with a warning not to actually try using the remedies associated with them. Often it is a matter of dosages being a careful balance between curing and killing the patient. I would think that any extensive herbal remedy book will also include a number of 'poisonous' plants as well.
