This plant grows like weeds my friend..
Ive got several pictures of plants that i have picked.. they resemble the opium poppy (papver somniferum) somewhat while theyre growing but once matured they sprout yellow dandelion looking flowers whereas the opium poppy just grows straight up and produces one single flower pod... if you really want to learn more about the Lactuca Verosa plant there is tons of information on YouTube... i have several pictures of Lactuca Verosa plants that i have picked.... there is actually one down the road from where i live that is about 7 foot tall but its underneath an overpass so i cant really stop my car and jump out and get it hahaha... i might try and snag it one day.
Well i hope you find all the information your looking for, if you have any questions feel free to ask me.. sorry it took so long for me to answer this post.
Have a great day!!

PS- sorry for the sideways picture, for some reason all my pictures do that.