Howdy y'all,
I recently found out that one of the "weeds" that always pops up around my garden is in fact prickly lettuce (latuca serriola), the ancestor of cultivated lettuce and, despite the prickles, a nutritious and tasty edible plant. I wrote a little paragraph on it here:
http://www.paleogardener.com/2011/07/plant-profiles-prickly-lettuce.html , if anyone is interested.