My husband recently tilled this section of our backyard and spread grass seed. After a couple of weeks, they usual 'stuff' started coming up...native 'weeds' and what looks like are two or three different kinds of grass and I'm fine with that. But this plant soon started shooting up, and out of curiosity, I asked my husband not to cut it down. So we let it grow to see what it would turn out to be. It is now approx 6 or 7 feet high, with huge leaves and beautiful, white trumpet-style flowers with touches of lavender around the edges of the petals.
There has been recent discussion of the plant and its relatives in this thread: http://www.botanicalgarden.ubc.ca/forums/showthread.php?t=16049&highlight=jimson
Addictive plant.... Caution, having a Datura will surely lead to more, you will want Brugmansias, in 300 varieties...the beautiful albeit short lived blossoms emit a scent , late in the afternoon, which is what captures the senses.... does your Datura perfume the yard during the late afternoon?
Well, we haven't noticed a scent, but then again, after reading your post, we've probably been sniffing it at the wrong time of day! I'm certainly glad I talked my husband into leaving it be.