I am not a constitutional scholar so a better expert may be able to provide a more sound response but I believe the Commerce Clause is generally accepted to include currency control (and early tests of federalism in the US found that independent state currencies could be restricted by the federal government).

From Article 1, Section 8: Powers of Congress:

The Congress shall have Power To lay and collect Taxes, Duties, Imposts and Excises, to pay the Debts and provide for the common Defence and general Welfare of the United States; but all Duties, Imposts and Excises shall be uniform throughout the United States;

To borrow Money on the credit of the United States;

To regulate Commerce with foreign Nations, and among the several States, and with the Indian Tribes;

...

To coin Money, regulate the Value thereof, and of foreign Coin, and fix the Standard of Weights and Measures;

...

To make all Laws which shall be necessary and proper for carrying into Execution the foregoing Powers, and all other Powers vested by this Constitution in the Government of the United States, or in any Department or Officer thereof.

Congress's authority in this area was upheld by the foundational case McCulloch v. Maryland in 1819. The Federal Reserve System was created in 1913 by Congress via the Federal Reserve Act.

There's no serious argument that the Federal Reserve is unconstitutional. People who espouse this are ignorant of the facts and law, or are either quacks or have paid heed to the arguments are quacks.

The Federal Reserve Bank is in effect a club of banks. They pay for it. It's not an appendage of the Treasury.

> The 10th amendment limits the federal government to the enumerated powers.

federal reserve is not government... that's kinda the entire point)

its why current US admin is being so butthurt about it, it's not under its control.