Growing up, the button box was always one of my favourite 'toys' and I would spend hours playing with it. Ebi-kun also does the same, he will sort them into colours or shapes, polish them, find ones with magical powers, making patterns in playdoh, flicking them around the floor in his own version of tiddly winks and other such things. Recently he has got a thing for treasure hunts, so I made up this button hunt to keep him out of mischief, I have made it into a PDF so you can download it and do the same. You could easily make a simpler version for non readers or one specific for buttons in your own tin.
If you need any more button ideas why not try....
Button cleaning (bottom of the post)
Button flowers and One More Moore
Threading felt with Montessori Mama
Button napkin rings at Copycat crafts
and if that isn't enough, there are a tonne of ideas here.