I am trying to remember/find a book about a little girl who doesn’t have much, except her little treasures.  I think it was a stick of chewing gum, a jack ball, and a few other small items.  She lives in a brownstone and it seems like she hides her treasures behind a brick.  She takes them out and looks at them often.  The front of the cover had her and another person sitting on concrete steps with a railing.  I don’t know if it was a little golden book or not.  It seems like it was about 5X5 square, about 10 pages?  I would have had it read to me around 1970ish.  I can’t remember much else.  I have looked everywhere for it, only being able to search by the memory of the cover.