My grandfather had a farm in Oklahoma after the great depression. There was a plant that the cows wouldn't eat and was over running the place. He tried removing it but it would come back year after year.
He was visited by "men in suits" asking about the plants. He being naive to it, told them how it was a nuisance and none of the cattle would touch it.
They came with a bunch of men later and ripped it all up and burned what was left.
Years later he recognized the plants as cannibis.