Hi Ed. If by lily of the valley, you mean Convallaria, that too would be invasive, at least to a degree. I like the fern idea, and while it sometimes gets a bad rap in gardening situations, the fully native and colonial species ostrich fern would do an especially good job of holding soil in place and covering the ground. It is this plant's very exuberance that would allow it to do so.

Cinnamon fern is likewise a great choice. Is there any shade here? I see ostrich fern growing in full sun up here in wet ditches, etc.

Cranberry or other Vacciniums like it on the acidic side. There're lots of grasses and sedges adapted to high moisture. Maybe one or more of them thrown in the mix?

+oM

This is a substitute for ivy for someone who doesn't do the native gardening thing. I figure anything other then ivy I can get them to grow is a win. Is Lily of the Valley less of an environmental problem then ivy?

No shade at all. What is ostrich fern like?

I generally don't like grasses, although I sort of like Northern Sea Oats.

Would any two of the plants I mentioned grow well together?

You'd just have to try them and see-as far as how these various suggestions would comingle. Ostrich fern is a classic-looking, very lacy fern, of considerable size and vigor. It is fully colonial in habit. Many, many an older home had these things around the porch, etc. until modern people showed up who, for whatever reason I've never been able to discern, eradicate them with gusto.

I've still got them in my back area, where they fight it out with other aggressive plants like Convallaria and Aegepodium. It's a good fight!

+oM

Hi: For a sunny location, Lady Fern might work. Not sure if it's native, and it spreads too fast for most garden locations, but I think it's less invasive than lily of the valley and not as tall as other ferns. Cinnamon fern grows along a wet ditch up in my Maine garden, and I think it's very attractive. I also saw a ground cover called blue eyed grass at Russell's in Wayland. It flowers and likes moisture I think. It looks more like a sedge than a grass.