My rocks came from a bag of those which were just called "river rocks"
or "river stones". I got them at a large home center (Lowes or Home
Depot).
Exactly! In Seattle, it's not a particular KIND of rock. It's just ROCK.
Unfortunately, here in my new home (Atlanta, GA) people give you a funny
look when you say something like that. Here, "just ROCK" means some kind of
tan rock. Of course, no one can tell me what kind of rock the "just ROCK"
out here is... because it's "just ROCK."