Originally Posted by C Of K
I have heard that their species is called the Whills, but I'm uncertain if that is canonical.
Isn't that the brother of Prince Harry?
Accordingly to Wookieepedia, Whills are not the name of Yoda's species but just a kind of Force Shaman or learned priest/monk. Apparently, originally Lucas planned the Whills to be something similar to the midichlorians, but then he changed his mind to the Force being some disembodied God-like higher power, and then again finally to the one all-powerful Force controlling everything and a mystical energy field controlling all our destinies. The references made to the 'Journals of the Whills' and the 'Ancient Order of the Whills' were kept in even though it was no longer relevant.