Kid's Stuff:
I'm a little hesitant to suggest this page is just for kids because there are clearly lots of grown-up collectors that collect insects, rocks, leaves and such. Arguably more educational than a lot of other collectibles you could name. There is also the fact that the collector probably actually 'collected' the goody rather than bought it.
Useful Links:
This is a great example of a site where-in the guy really loves his subject and know what he's talking about. Check out Bug Collectors , and stand by to learn something.