LOL. I had just one plant but all the seeds that dropped that I didn't get harvested will return a basily yard next year. We don't have any that grows wild but we have wild onion. lol
We currently have some spearmint that we planted a few years ago. It's growing wild because we rarely cultivate it but don't have the heart to pull up this sweet smelling plant (and we do use the leaves from time to time).
I had mint at my old house and that's how it did. I pulled it up by the hand fulls and gave it away. I gave a bunch to my mom and now it's growing wild. It multiplies by the root and seed. So when it spreads, IT SPREADS! lol