Sorry I just saw this one too. Corn I think is going to be a no go on the west side at least- for bulk grain orders anyway. I am unaware of any, and I'm in a possition where I'd kinda expect to. Wheat, Rye, and Barley though are totally doable. The three bulk producers which spring to mind are
Gibbs Organic Farm which is just over the crest of the cascades. Grant Gibbs is an awesome dude with an astounding depth of knowledge. I'm sure someone would be able to advise you if you email them and give them a rough pre-order
http://www.gibbsorganic.com/
Nash's Organic Farm outside Sequim. Again, great people who have always been exceptionally generous both with their produce and knowledge.
http://nashsorganicproduce.com/
There are also several families on Ebey's Prairee who grow grains. I believe they pool together as basically a co-op when they
sell, but I'm not sure. Best quick contact info I can find
http://www.agrilicious.org/Ebeys-Prairie-Grain-Co-LLC
I don't know whether the Bishops or the Shermans or who are the major interest but some internet poking would probably turn up the proper contact info if the above link proves fruitless.
Good luck getting grain!