Cockleburs are a weed that is odd.
By odd I mean each seed pod or burr has 2 seeds. One will grow next year and the other year after next.
So to kill them you have to control every weed for 2 years in a row to get them.
We fight them here and the best control is a hay field for 3 or 4 years that is mowed 2 more times a year.
They also like to come up late after you can no longer get down the rows of corn or beans.
Good luck I'm still fighting them here.I think I'm gaining on them.