Those appear to be Russian knapweed.  They are toxic but the probability of livestock consuming them are pretty slim.  I have attached a couple of documents concerning Russian knapweed and it's control.  Also, one of the fastest ways to determine if it is Russian knapweed is to pull a plant up and look at the roots.  They should be dark brown/almost black and have scales.

https://extension.colostate.edu/topic-areas/natural-resources/russian-knapweed-3-111/#:~:text=Russian%20knapweed%20is%20toxic%20to,and%2For%20chemical%20control%20techniques.

chrome-extension://efaidnbmnnnibpcajpcglclefindmkaj/https://sam.extension.colostate.edu/wp-content/uploads/sites/2/2018/01/NoxWeedMangementGuide2014TRADelta.pdf

I hope this helps!

Doug