Outer coastal native fern Polypodium scouleri would probably fit in nicely, maybe you could get Woodwardia fimbriata to grow also - if you don't have these already.

Are you familiar with the wooded part of the garden at Heronswood, near Kingston? It is similar to what you are doing in these pictures, but farther along in development. Another place where you can see similar plantings is the lower part of the Rhododendron Botanical Garden in Federal Way. It is immediately east of I-5, with freeway signs telling you where to get off.

I have P. glycyrrhiza growing on some of my trees, the rhizome are licorice flavored while P. s isn't. I wish I had some Woodwardia fimbriata growing on my place. It is hard to find both in the woods and in nurseries.

I'm not familiar with Heronswood, except by pictures and ordering plants, but I am a member of the RSF garden at Federal Way. I have been for many years, and enjoyed walking it a long time before I became a member.

I bought this place from people too old to take care of the grounds. Because of that I have a lot of exotic weeds such as English ivy, a very small leaf ivy, English laurel, English holly, European beech (both green and red leafed), European ash, European sweet cherry (P. avis), along with several other escaped garden plants growing on the lot. The previous owner planted the english ivy as erosion control, but over the years, timbleberries, salmon berries, elderberries, and european ash have grown up through it and is starting to shade it out. On the part of the lot that is dryer I have salal growing up and out competing the ivy. I just moved here with a large collection of potted plants and in ground plants I dug up from my rental place in Issaquah. So I haven't had time to clear most of the forested area out of weeds to make room for my plants. Now that I am retired I hope to get this place in shape.