We went out this morning for the third time to eradicate this stuff from one of the fields. It is called Jimsonweed (Datura Stramonium) and is sometimes called Loco Weed because of its toxic and halucinogenic properties. You can read more about it: http://www.ansci.cornell.edu/plants/jimsonweed/jimsonweed.html or http://en.wikipedia.org/wiki/Datura_stramonium the latter being the more interesting. Anyway we have spent hours walking the field and cutting these buggers off at the roots with a shovel.