You can also use the little volunteer as a watering aid for either the basil or capsicum, which both like it dry. If the volunteer wilts before the others do (it likely will) you can wait to water until you see evidence of it wilting. I often allow volunteers to remain in my containers of plants that prefer a dry soil (pines, junipers, etc.) for just that purpose. Al

It would have to be something with seeds that can be distributed by air in Seattle. This soil was used for growing last year, and I haven't added any, so there shouldn't be anything new from other routes.

They look like pokeberry to me; all parts poisonous. Next time, you may want to post under "Name that plant". The experts there are always willing to help you.

Hmm, well the smell isn't fruity or what I would describe as 'pleasant', not sage-like either...I'm hoping it will flower for me so I can post a picture. The leaves aren't strong smelling...hard to describe the smell, sort of skunky but not pungently so.