Answer: It's really difficult to identify a plant without seeing it, but I wonder if the plant is Jerusalem Artichoke, (Helianthus tuberosus) which sometimes escapes cultivation and can be found growing nearly anywhere in the Pacific Northwest. You might take a flower and a few leaves to the Cooperative Extension office (or a few photos) there in Bellingham. Helpful folks there can positively identify the plant for you. Best wishes with your garden!
Q&A Library Searching Tips