When I need to know about something specific, I start searching for just that thing. If you can find the Latin name of the plant, that might help too. A lot of common weeds are known by more than one name.
It can be hard to find common names of weeds at times. I'm sure there are apps that will...
Your google-found lists are probably an excellent starting point. Here's another place to look.
https://www.backyardchickens.com/threads/the-definitive-list-of-chicken-treats-what-can-chickens-eat.1273191/
USUALLY, chickens won't eat something poisonous. (I know nothing about geese.)
You can...