Pair of Vintage 1960s US 5 cent Postage Stamp First Day Cover FDC Envelope

Pair of Vintage 1960s US Postage First Day Cover (FDC) stamp and decorative envelope set.
1966 5 cent US Postage stamp featuring the flag of the USA and the White House
1967 5 cent US Postage stamp commemorating Canada's centennial (1867-1967)
Envelopes measures aprox. 6.5" x 3.5".