the flicker is indeed a full-fledged member of the woodpecker family (Picidae). if it was a flicker in portland, it was undoubtedly a red-shafted flicker -- they're year-round urban residents. as for the red on the head, the males have a red moustache-like patch, the females don't. from your description it sure sounds like a female red-shafted flicker -- looks like you came to the same conclusion. if you see it again, watch for it in flight: it should display a noticeable white patch in its rump. if you live in portland, a handy book to take a look at is Birds of the Willamette Valley Region by Harry Nehls, a local Audubon Society stalwart and all-around good guy.