Claydonia rangiferina.

Botanical name: 

Claydonia rangiferina (Linn.) Web. Lichenes. Reindeer Moss.

Northern regions. Reindeer moss is sometimes eaten by the people of Norway and is crisp and agreeable. Reindeer moss, says Kalm, grows plentifully in the woods around Quebec. M. Gaulthier and several other gentlemen told him that the French, on their long voyages through the woods, in pursuit of their fur trade with the Indians, sometimes boil this moss and drink the decoction for want of better food when their provisions are exhausted.

Sturtevant's Edible Plants of the World, 1919, was edited by U. P. Hedrick.