Sorry, don't know how to post more than one pic at a time so here's more.

Is it Silene latifolia (White Campion?)

Well, maybe either that or silene vulgaris, bladder campion. Just looking at a book on PNW native plants in the wildflower section, I read that the white campion is similar to silene vulgaris but that the difference is that the white campion has male and female flowers on separate plants and has blooms with 2 lobed petals and 5 styles.

The vulgaris has petals that are deeply 2 lobed at tip and there are usually 3 styles.

I can't tell from looking at the picture; does the bloom have both male and female parts on it?

At any rate, they are both native to Europe and are an introduced perennial. They seem to be most everywhere in the US.

They grow from a taproot; whether it will be invasive, I don't know. My definitions are: If you like it, it's a flower. If you don't, it's a weed.