I have various plants that came from humble beginnings. One came from a refuse hopper and the other from a golf course.
I found two prickly pear lobes sticking out of a hopper. Our garden was bare and new so I was finding plants for certain sites. The prickly pear lobes I placed in a hole in our fruit garden. The plant is now a large size, at least a metre and a half. It produces orange prickly fruit. Yearly, we have to hack it back as it grows happily.
As I approached a golf tee I noticed broken pieces of cactus nearby. Obviously, this plant was being hit by enthusiastic golf swings. I placed one piece in my pocket. It felt scratchy as I played but once at home, I planted it in a pot. Soon I had to move this cactus to another area. It became massive and a good thorny boundary shrub.