Possible Clues:

• The "E" of BPOE
• Group with a Grand Lodge
• The 'E' of 'B.P.O.E'
• Plural used for people but not animals
• B.P.O.E.
• They have palmate antlers
• Some service club members
• ___ Club
• Yellowstone beasts
• 153-year-old group that became unisex nationally in 1995