I fully understand your requirement.
I've done some works on children's book in my university workshops and very friendly with children through many experiences. Also I create hand writing illustrations for my story. (You wouldn't need it though.) I have my own collection of children's book (around 700-800 books in my bookshelf), so I am still enjoying and containing hearts for beautiful short stories.
If you give me he specific guidelines for the story (words for each page, total number of words for stories, which target aged children would read the book, etc), it would be much helpful for me.
I'll gladly send you the sample story if you require.
Thank you.