Tokens and Treasures. Information on this National Archives and Records Administration exhibit of selected gifts received by American Presidents beginning with Herbert Hoover in 1929.
From the site:
As the highest representative of the people and government, the President accepts gifts on behalf of the United States of America. The phenomenon, as old as the Presidency itself, grows with each administration: Today a President may receive 15,000 gifts a year. They come from every state in the nation and every country in the world. Gifts from foreign leaders continue a rich diplomatic tradition of exchange between heads of state; those from citizens, both Americans and others, symbolize an inherently democratic exercise - ordinary people freely addressing, in every manner and form, the President of the United States.