John,

Anybody can create or edit entries at the Wikipedia site. If you click on the "History" tab for any particular entry, you can see who edited it and when. In fact, if you click on the History tab for Casino_Chip_Collecting that Greg posted a link to, you'll see my name.

Of course, somebody else can come along behind you and edit your entry, which can be good or bad. And, they also have lots of rules you need to follow. I created another entry for small_crown_chip and added a scanned image to show what one looked like. Somebody came along later and removed my image because I didn't give the proper source information for it.