US Secret Service - the United States intelligence agency that protects current and former presidents and vice presidents and their immediate families and protects distinguished foreign visitors; detects and apprehends counterfeiters; suppresses forgery of government securities and documents.
It's  blessings not blessing.. The entire clause is ...to secure the  blessings of liberty to ourselves and our posterity....    The blessings of liberty refers to all of the benefits that are  afforded by having liberty.
There is a poem printed on a plaque that sits prominently outside the Statue of Liberty in New York titled The New Colossus. There was a Masonic cornerstone ceremony and plaque placed on the cite as well. The statue also symbolizes a composite of variety of ancient goddesses who represent the feminine principle.