We have lots of volunteer weeds. does that count? :-)
We used to have a rhubarb plant when I was a kid that you just couldn't kill, even with the lawn mower. (and I tried!)
It spread itself around the borders of the vegie garden after a while.
So what to do? Well, as kids we started eating it while the stalks were young and juicy.
It still didn't die, but we had some good vegies in us. :-)