There is a fairly low-key summer crit series in eugene, an easy 55 minute drive from Corvallis. They happen every Tuesday evening from June through August, check the racing schedule at obra.org for more info. Its a nice wide flat crit, with decent competition but nothing too serious. I try to go at least twice a month after work. I live in Corvallis, PM me if you're interested in car pooling sometime this summer. Also, Eugene has a hill-climb time trial every Tuesday in May. Its short and casual, and lots of fun (and painful).
There is a group of racers who race for the EWEB team, but live in Corvallis. They are mostly 3's and 4's, and they ride T/Th evenings all summer. Saturdays you have your choice of the large group ride at 8am or the OSU team ride at 10. Both are fun and well attended, although OSU attendance drops off after school is out.
Corvallis has a great cycling community, great roads and training routes, and Oregon in general has a very active racing scene... besides the rainy winters and logging trucks its a fantastic place.