Generally chickens know what to eat on their own. In my backyard I have things that are bad for chickens. Lillie's,, Tomato plants,, Yew trees,, Nightshade growing thru neighbors fence,, and probably others, I missed noting. My chickens do not snack on any of these. They choose what they like, and it does not seem to be the poisonous plants. Have been keeping chickens over 20 years now, with no instances of chicken deaths due to poisoning.I need a chart of what weeds the chickens can't eat to clear them out,
I do have a chart listing ALL,,, or most of the common plants that are toxic to chickens. That list is longer than my driveway to the street
I will try to search for it , but just now, I don't know exactly where I put it.
It may be similar to California's' Warning. Where even tiny trace amounts or category to be included on product label.
I'm not writing this to start a debate on California's Warning Policies, Just pointing out that if a chicken tries a small peck of a poisonous plant,,,, they do not automatically die.
There are tables that list "Lethal Dose" amounts (of various things) which include water for humans.