Sword ferns are easy to move too, if you can find some in the woods. You can even dig them up and split them into a few smaller ones.
Now is a good time to move them, before this year's new growth comes up.
Yeah - that's probably a lot of traffic for a small shady yard. Even for grass! Stepping stones of irregular size and shape, with a few inches between them, might be good. Grass could grow up between, particularly if you said you didn't want it to ;) Could be pretty and less muddy for...
I'm in W WA too. It's the worst part of winter right now for the grass, but we're just a couple of months from grass growing out of our ears whether we want it or not, if you can bear with it a little longer. :)
It wouldn't hurt a lawn to put down some chopped up hay or straw to give a...