I'm kinda busy right now, actually updating my research for a presentation this summer.

I've been working with a handful of THE major researchers for 10-20 years now.
THEY have all the locations, dates and photos...archives.
Colin Andrews (a good friend of mine) has an archive of over 4,000 circles in over 50 different countries alone.
I have access not only to his data base, but a couple of others (US and Canada).
As a matter of fact, I just got the list from Canada that has 130 locations and formations from just the years 1995-2005.

>Have they all been documented, photographed, and authenticated?

Documented yes, photographed IF the farmer had a camera, and took some shots of it.
Authenticated is another story, that takes a lot of work, and besides gathering samples, you need to work with a lab that won't charge you. You have to be well connected. And able to travel at your leisure. All this stuff costs money; which is why some researchers take their time.

Colin Andrews was funded by Rockefeller for years. He is well known in the field and considered an authority on the <subject.>