THE REAL SPOILER: they are a gift from us to them.

Title 31, "Money and Finance." (d)(1) The Secretary of the Treasury may accept, hold, administer, and use gifts and bequests of property, both real and personal, for the purpose of aiding or facilitating the work of the Departments of the Treasury. Gifts and bequests of money and the proceeds from sales of other property received as gifts or bequests shall be deposited in the Treasury in a separate fund and shall be disbursed on order of the Secretary of the Treasury. Property accepted under this paragraph, and the proceeds thereof shall be used as nearly as possible in accordance with the terms of the gift or bequest. (2) For purposes of the Federal income, estate, and gift taxes, property accepted under paragraph (1) shall be considered as a gift or bequest to or for the use of the United States. (Title 31 U.S. Code § 321. General authority of the Secretary(d)(1)(2))