U.S.A., Postal Seal, New York, Image & Found by Ian Artyparty Johnson.
Found near Ormskirk, West Lancashire, 18x17mm.
U.S. / MAIL // NEW / YORK
The United States Postal Service (USPS; also known as the Post Office, U.S. Mail, or Postal Service), "is an independent agency of the executive branch of the United States federal government responsible for providing postal service in the United States, including its insular areas and associated states. It is one of the few government agencies explicitly authorized by the United States Constitution. ... The USPS traces its roots to 1775 during the Second Continental Congress, when Benjamin Franklin was appointed the first postmaster general; he also served a similar position for the colonies of the Kingdom of Great Britain. The Post Office Department was created in 1792 with the passage of the Postal Service Act. It was elevated to a cabinet-level department in 1872, and was transformed by the Postal Reorganization Act of 1970 into the United States Postal Service as an independent agency."
It is possible that they are British Post Office letter bag seals from mail on its way to New York. The shape is very similar - Post Office GPO Square Seals.