Right here at True Mushrooms, we use the cultivated substitute, Cordyceps militaris. It's the only kind of Cordyceps species that could be commercially cultivated at scale to provide a mushroom (fruiting overall body), and it is starting to become rather well-known for use in health supplements. When taken by mouth: https://codyfnrgt.thezenweb.com/chaga-for-dummies-69986137