Lot of 6 Postcards First Day Issue US Postal Service Poland British Empire

Lot of 6 Post Cards First Day Issue US Postal Service Poland British Empire US postcard and Postal Service FDC have paper clip marks. British Empire post card has creased corner. Postal Service FDC has stain at bottom front. See photos for condition. Lot includes: Poland post card British Empire 3 pence postcard US 6 cent postcard US 4 cent postcard (US Customs) Inaugurating the US Postal Service First Day Issue Centennial of Sound Recording First Day Issue