The Milk Thistle got cut down to just the stems (I don't know the proper term).
Then I used the Round-Up. Results were great.
For the past few months, I've sprayed Weed-B-Gone concentrate 3 times to rid the yard of crabgrass and broadleaf weeds.
Friday, I noticed these flowers throughout the whole pasture, and, many locations in the yard. The second and third pic, below, is in the yard. They don't seem to be affected by the Weed-B-Gone.
I've been Googling pictures of purple wildflowers and I believe they are, but, none are exactly the same.
I did send another email to the herbarium for positive ID, but, I am wondering if anyone here has any idea of what it is, and, how to get rid of it from the yard.