I've collected so many from roadsides, abandoned home sites, and from friends who often knew them as "grandma's blue Iris" or "white cemetery Iris". Often the story behind an Iris makes it all the more meaningful. Some of these are old historics, others more modern, but I'm pretty sure most are over 30 years old (since introduction).
"...and don't think the garden loses its ecstasy in winter. It's quiet, but the roots are down there riotous." Rumi