Safe to feed?

[The_Four_Toed_Edward]

Is this safe to give to my Russian tortoise? The leaves are new to me.

 

[The_Four_Toed_Edward]

I am thinking hawkweeds (Hieracium), Bristly Oxtongue (Picris) or Sowthistle (Sonchus).

What do you think @RosemaryDW ?