Is there a place to find extremely simple stories?
Possibilities here

I sometimes read essays written by Chinese children: RuiWang's 作文.  They have all levels for free, starting from 一年级 (grade 1).

You can find many English novels translated into Chinese and available for purchase on JingDong or other sites.  I read Matilda (玛蒂尔达) this way.  I thought it was helpful for improving my reading speed.

You can access Chinese school textbooks for free at 电子课本网: the reading material is 语文.  Again, starting from 一年级 (grade 1).  [After selecting a book chapter, it looks like you need to scan a QR code, but you can just click it and it'll show you the pages.]

Du Chinese is a well-polished reading app---new material is free [it's also new and fresh], and I feel it's reasonably priced for what's clearly a lot of effort.

Hacking Chinese reviews Mandarin Companion's graded readers which are here.  (There is also an article about 语文 which is more advanced.)



There's a list of resources here: Resources for learning Mandarin Chinese, but it's cumbersome.  These kinds of resource questions is why I wrote this post on meta (although it hasn't caught on).
I also note that many books are available for download from Blah.me.