Here's a link to a
website on the Sovereign/Freeman on the Land idea. As you'll note, this is not an FBI brief, it is a site created by an actual Freeman.
These ideas espoused in this link are not rare, they are commonplace and can be found if you know the "Buzzwords". Searching for "Sovereign Citizen" will pull up reports from SCLC and ADF.
Search "Gold Fringed Flag" "United States v United States SCOTUS" "USA is a Corporation" for good lolz.