Hi Robert, and welcome
Off the top of my head, the only white one I know for sure is a re-bloomer called "Immortality". Does yours sometimes re-bloom in late summer or fall?
May I suggest you post your lovely pictures on this thread (link below) in the Irises Forum? It's entitled "Show us your NOIDs" and a NOID is an iris with "no ID". That way all the iris experts will see it, and be able to help out.
The thread "Show us your NOIDs" in
Irises forum