Gum

I can't believe it took me as long as it did to realize this and it is going to make me look like an idiot but here goes.

I've noticed all these...little discs...on the sidewalks and places. I thought maybe it was a lichen because you see moss on everything. Or maybe bird droppings but way too many. Or some repair thing.

Well, I finally figured it out. It is gum. There is gum everywhere! It gets squished and squashed and is never sticky so there are these white and grey discs everywhere. Especially around the rare rubbish bin.