Well, there could be all kinds of stories in it. Maybe some about animals having little adventures in the forest. For example, a squirrel finding a new tree to live in and the challenges it faces during the move.
It could also contain stories about the magic that exists in everyday life. Like a flower that blooms in an unexpected place and how it brightens up the day of the people who notice it. The 'big book of little stories' might be filled with such heart - warming and thought - provoking tales.