These stories have all basically been debunked. Monsanto did sue farmers. But they did so in cases where they had evidence that those farmers were not only planting IP-encumbered seeds, but also spraying them with Roundup. You can't do that accidentally: if your seeds aren't genetically modified, Roundup kills your crop.
Yep. Here is another comment of mine where I breakdown one of the most famous examples:
https://news.ycombinator.com/item?id=46176059
And another comment where I discuss another example and their legally binding declaration to not sue over accidental contamination:
"IP-encumbered seeds" is a wild phrase.
The entire concept of IP-encumbered seeds is cruel and dangerous.