Plants that are signs of former human settlements
I think an equally interesting point might be why Daffodils tend to outline the foundation of where a house used to be. Yes of course because people planted them there but then you'd expect wild animals to eat and carry the seeds away. Which would mean that the daffodils would expand out adding some background noise; this doesn't happen though. My theory is it's because not many animals eat daffodils and spread the seeds around.