I agree with Kristyh. Definitely dandelion and oxalis in first picture, and dandelion in second picture. Both plants are completely safe for chickens to feed. Oxalis is high in (surprise!) oxalic acid, but so are many other wild plants.
Chickens that are fed a good diet and allowed to forage for weeds will usually eat a variety of plants, while not eating excessive amounts of any one type of weed.
That said, if chickens are fed only one type of wild plant, they could be susceptible to nutrient imbalances just like their humans!
My chickens love my hostas more than any other plant here on our little homestead! It is impossible to keep the girls out of the hosts beds.