A collection of very old stamps and envelopes that I know nothing about.

I have acquired a collection of nine envelopes preserved in individual plastic covers: martin Dawson Company from 1899, International Stock food co. 1809, The Natural Food Conservatory 1906, two envelopes from H.J. Heinz company 1917 &1915, Vaughans Seed Store 1917, Builders' Hardware1904, Buffalo Forge Com 1904,American Wholesale Corp 1928and a calendar for 1880-1925, on celluloid, mechanical copyright 1890 of the Otis Elevator Company Perpetual Calendar all with beautifully drawn depictions of the sites. I also have a 1977 baseball card from ToppsChewing Gum inc. and about 70 stamps from various countries and 8 cent Eisenhower4 cent Lincoln, 5 cent Air Mail USA, A red 2 cent stamp with a profile of a president on it "Washington I think" 14 cent united nations stamp with a colored tree for fundamental human rights, 4 cent project Mercury stamp. I really don't know how valuable any of this is so if anyone has any idea feel free to share :-) Thanks.