Native Aquatic Plant propagation

Hi!

I get a lot of conflicting information from folks who ought to know (given their employment,) about what is and what is not a native to the Pacific NW rivers and what is and is not okay to collect.

It has been my observation in my tropical aquarium that aquatic plants are about the easiest plants in the world to propagate. I can take a ripped up shredded piece of nothing, stick it in the gravel, and a plant will grow from it. (Unless it's an expensive plant, which we all know dies the day after you buy it.)

I don't really live to go dig up plants, "pillage" the environment, and get yelled at for doing so... does anyone know:

aquatic plants native to the Pacific NW (Oregon, specifically) that propagate easily from a leaf clipping or seed? And if so, when is the best time to collect these?

Time is not a factor, I don't need big plants today, I'm happy to wait if I know I'll be successful.

Thanks!

Mander