Chaga

On a recent canoe trip I was able to harvest some chaga or tinder fungus which grows on birch trees.  The Wikpedia page has a pretty good description of the stuff.

Chaga right after it was harvested.

It makes an excellent tinder that once ignited using a ferro rod or magnifying glass is nearly impossible to extinguish, hence it's nickname "tinder fungus". This piece smoldered for at least fifteen minutes and released a pleasant aroma similar to incense burning.

Burning Chaga

 It also has a history in Russia of being used to make tea which I have yet to try.