The Freemasons was a "secret" organization that the majority of the founding fathers and early Americans were apart of. Benjamin Franklin, George Washington, and many others. Lots of easter eggs are hidden in the Government and History as a whole relating to the Freemasons.
Freemasonry is based on fraternal organizations that trace their origins to the local guilds of stonemasons that from the end of the 13th century, regulated the qualifications of stonemasons and their interaction with authorities and clients.
While Freemasonry has the appearance of a religion, they are in fact a secular group, although they insist that people who join believe in an absolute being. Started in Scotland, it soon moved to England.