Looks like one of the genus Noctua underwing moths. In the PNW, we have the Greater and Lesser underwing moths. The larvae feed on quite a variety of annuals. The caterpillars can be quite numerous and are more active at night, right down to freezing temperatures in autumn. To see the brown adult moths, just spray some water in your shrubbery and some might fly out.

(Do not confuse with the more showy genus Catocala underwing moths)