Iris douglasiana is a native of California and Oregon, ranging in color from white to cream to lavender. It's in the parentage of Pacific Coast Irises. (PCIs are tricky outside of their western environment.)
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A list of Iris douglasiana cultivars at American Iris Society.
http://wiki.irises.org/bin/view/Spec/SpecDouglasiana
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I'm sorry not to have a source. Maybe you'd enjoy seeing related PCI's?

http://aitken-garden.goodsie.com/pacific-coast-iris

Joe Ghio has hybridized lots of PCIs. Don't believe he sells online.
http://montereybayiris.org/gallery/ghiopci07.shtml

Here is a link that might be useful: Ryan Grisso hybridizing PCIs

Can the kind person who private messaged me please respond here. I received your message, but there was a note at the bottom saying you did not allow your email to be shown, so I can't reply to you. It also didn't have your username. I would love some Douglas iris from you.