I regularly use Birch Polypore Fungus as a fire starter.
I even include it in my "Dragons Breath " flint and steel sets as it is so easy to get a flame from.
The secret is to keep the fungus in your spare bedroom until it is realy dry then cut it into slices (I cut it from rim to tree attachment point with vertical cuts).
When you want to use it, take a slice out and shave ultra thin slices from it (if you carry it cut too thin the slices break up too easily). Hold your ember/glowing charcloth/cramp ball between two slices or in a tube of fungus and blow on it.
Result a hot strong flame that will not blow out or died too easily.
Works for me every time!
Rough up a thin slice and give it a good shower of ferro sparks and it will, 7 out of 10 times, catch the spark and burn.....all depends on how dry, thin and rough the fungus is ....