Agree with
@mangalavara : rainfall and birdsong (though
not magpies or green parakeets).
Sounds that drive me nuts: redundant and intrusive public address announcements. One example is on public transport, giving you information they gave you 5 minutes ago. But the worst of all is those TVs, imbecilicly provided in waiting rooms at airports or in doctor's surgeries. They run a never-ending stream of global disasters, which is not what you want to watch in those circumstances, and they prevent you concentrating on anything else. Nobody watches them. I've taken to turning down the volume so we can all get on with our books, magazines or internet scrolling in peace.