A unit focused on collections?

I'm thinking of designing a unit around collections of stuff.  This books is inspiring that...
 In Flagrante Collecto (Caught in the Act of Collecting)

And of course, this website... http://collectionaday.com/ and the book that resulted from it. 

Here's one for kids...

  Collecting Things (How to Make Series)


Probably the unit could be adapted to a science or social studies unit of study...
collecting rocks, collecting leaves, collecting seeds, collecting insects, collecting state quarters.