Answer: Angel Trumpet (datura) is not winter hardy, so you will have to start new plants each year one way or another. It may self seed, but it is more reliable if you start some yourself, too. Many gardeners take cuttings from their best plants and overwinter them indoors; this way they have larger plants to set out the following spring.
Unfortunately I can't give you contact information from the Q&A. The National Gardening Association http://www.garden.org
has a seed swap for interested gardeners .
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