Here is a sound recording good to listen to (more than once!) to get the full awareness that endorsing a check is endorsing the Fed. But... There is a remedy through Title 12 U.S.C § 411.
Making a demand for lawful money on the back of checks and then signing (not the other way around), takes You out of the Federal Reserve system. So... If We start doing this, We have no tax liability, having no contract with Them. They know it, too, and seem to comply. There's much detail here and I recommend You listen at a meal, or while tatting, or surfing the web.
Listen, research, and choose accordingly for Yourself. [smile]