Check out
http://www.intatrials.com/ Inland Northwest Trials Association is based out of the Spokane area but have rides a couple times a year in Connel. I sold my last trials bike (to buy my XC250) to a guy in Walla Walla and I think he said he was in a club based in the Tri-cities. There are classes for all levels and all age groups are in all of the classes, you won't be disappointed. I started learning by riding off-camber around and over a dirt mound, and with cinder blocks that I would stop the front or rear tire on, then restart while trying to keep my balance. Also bouncing the front tire off of trees (about 4' up) It definately helped with my off-road skills. One of these days I will get another trials bike (GasGas of course) and ride trials again. Do It!!
Jeff.