Natural Roofing Options?

Hi All,
What are some natural roofing options you can think of? I'm looking for alternatives.

Steel - fairly inert, but can come with some nasty coatings
Slate - natural, expensive, not easy to make or find
Wood shingle - natural, can be expensive, possible for someone to manufacture and install themselves

What other options are there?

Is there any thing more natural than an earthen roof aka as a green roof or living roof?

https://permies.com/t/102929/Living-Roof

https://permies.com/t/62028/green-roof

And another alternative is a thatch roof:

https://permies.com/t/5499/thatch-roofs

Ceramic rooftile.
I would not classify steel as natural.

Birch or other kinds of bark should be abundant in your region. I wonder if small loggers would let you take some? However birch bark can be safely taken from the living tree. They are sewn together into long strips horizontally, or held in place with the help of poles or sod.

Cattail matting is a lost art that I hope to learn…

You can use quite a few different materials as thatch. Many tall grasses like timothy can be suitable, as well as goldenrod stalks (when thickly placed). In some parts of the world, I think I remember that among the Mayans cornstalks are traditional thatching material. Phragmites (reed grass) is used in Europe so if you know of large patches those would work; however with stiffer stalks a softer grass is needed for the peak of the roof. (In France I’ve heard that people even plant irises in the thatch!)

You may want to peek at the Forgotten Arts and Crafts by John Seymour, that’s where I read about the softer grass (long wheat straw usually) being used for the peak of the thatch.

I am surprised that no one has mention wood shingle or slate.

I believe there have been some mention of bamboo as a roofing material here on the forum.