Smithsonian 150th Anniversary Stamp, February 7, 1996, Smithsonian Archives - History Div, The new Smithsonian 150th Anniversary stamp. It was issued February 7, 1996 with a short ceremony in Baird Auditorium unveiling the stamp. Sheets of the new stamp and envelopes with first-day cancellations were available for sale in the Rotunda of the National Museum of Natural History..