Is this a safe plant to feed to chickens? Help with iD

[Beldenfarm]

Hi all! I have quite a lot of this plant growing in my garden now that the crops are dwindling down, I cannot seem to find a proper ID for it and of course can't seem to find my field book! I would like to know if it is safe to give to the chickens for some extra green eats! I want to give them as much green before snow starts!

Thanks!

 

[Kelsie2290]

A young thistle plant?

 

[Beldenfarm]

The plant isn't prickly in any way, very easy to pull up! It seems thistle like based on the leaf shape but no prickles!