I'm not the best at plant ID and not familiar with what grows in the PNW. But if they took root in unoccupied planters it's probably something that grows wild around you, or something planted not too far away. Maybe walk around and see if anything looks like it in your neighborhood?
Sumac...or maybe some type of locust tree. Google-image those + your location and see if anything looks familiar.
Want to reply to this thread or ask your own question?
You'll need to choose a username for the site, which only take a couple of moments. After that, you can post your question and our members will help you out.