It is growing in an abandoned pasture with sicklepod, ragweed and other weedy sorts.
The leaves are opposite, serrated and narrow at the tip-oblanceolate
The inflorescence structured on cyme with 3 peduncles, below 3 peduncles, below 3 peduncles. The individual flowers are supported by a urn shaped calyx, with violet-blue hairs and pinkish yellow petals above.
The stems are square and pubescent like a mint, but the flower head suggests an aster.
I can’t seem to find a suitable identification. Initially, Trilisa seemed to fit but the structure seems of as well as the stem color.
I hope I have used the correct terminology. The drawing shows the inflorescence.
Thanks for your help
your plant is a non-native species, Verbena brasiliensis, the Brazilian vervain. It is fairly common in weedy areas. The additional images you sent of the actual plants gave me what I needed.
I hope this helps.
Dr. Steven Hill, Botanist SCNPS