I have a ton of buttons - I loved filling my big jar with buttons a few years ago (I bought tubs of buttons whenever I found them) They are handy to "find" an exact match for pants or a shirt.
As a child I remember visiting a friend's grandmother and sorting and playing with her multitute of buttons (back in the simple days- God I am getting old) .
At first I selected two simple buttons to draw, then looking at my jar I just had to include it too.
A fun challenge
Pen sketch in molskine journal then water color added.