I think that when you all have been chicken raisers for a decade you will find they are going to be okay
when they free range they generally know what to eat and not eat
Now when chickens are penned up then you need to NOT THROW any plant that is listed here into the pen
I always planted in my garden Swiss chard
several colors and as cut off above the bottom of the plant it grew back and made more good dark greens for chickens
I never had any trouble with the garden stuff as I knew that tomatoe vines and potatoe vines are bad for chickens
So try not to worry about what is good and what is bad
Kind of like people, those that grow up in the city or the country seem almost clueless when out of their element. What's danger, what's not, etc...