Grass left to its own devices. I have a few friends who are passionate about wild gardening/biodiversity/ sustainability etc and a few who think that's awful and just an excuse for not putting any effort in.
I'm somewhere in the middle so have a neat lawn and flower beds but also a wild area including a pond and plenty of plants for the pollinators. I left an area of grass unmown but it seems to mainly attract my cats. They love it in there,