itch.io

I found it. Previous comment just mentioned i was looking for it but didnt know where ive seen it. Shortly after....

https://itch.io/post/10252708

You have to read the whole essay - answer. 

You mean in game right? You can find it randomly on the background there are specific areas where the money respawns, off the top of my head it's the fountain at I believe the middle of the night, in some planters behind a classroom. I think the money doesn't start appearing until you progress the story and some characters will pay you for fetch quests or buy certain items off of you.