PNW stands for Pacific Northwest Iris Growers, also known as the Oregon Trail Iris Association. The club has a rhizome sale in Oregon every fall and then offers the remaining rhizomes to us at a great price. The club members are some of the big names in commercial iris growing, and many of the irises offered are newer ones.
If you follow the link in the first post of this thread, it will take you to the Iris Cubit, where the sale is conducted. More info will be posted there soon.