I own several Van Gogh paintings, some dinosaur skeletons, and Abe Lincoln’s hat - And so do you

See something da Vinci painted. Study the bones of an eons-old giant, armored fish. Honor the memory and legacy of Abraham Lincoln. Marvel at bizarre Soviet space capsules. And, leave your money at home.
Like archives (which I wrote about some time ago), museums offer opportunities for people to make use of common wealth, to learn, and to interact with each other. By sharing artifacts and works of art with other members of our community, we enjoy their benefits without having to personally bear the costs for their protection and care. (How do you clean a stuffed chimpanzee in a space suit, anyway?) This public ownership and use is also a means for creating and building value without making more stuff that will just be thrown away.
For those who want to learn more about the natural environment, its histories, and the ways that other people (past and present) perceive and relate to it, many museums have much to offer. Aside from obvious option of natural history museums, many art museums and galleries offer exhibits on landscapes or nature photography, while history museums frequently tell stories of the reciprocal influence between people and nature.
For those living in the DC area, these treasures are offered to the public virtually every day, free of charge at the Smithsonian Museums and at the National Gallery of Art. For anyone in the area interested in an outlandishly cheap* way to be the solution there are some great environment-related exhibits going on now:

Freer + Sackler Galleries:
Winslow Homer: Four Views of Nature

National Air and Space Museum:
Looking at Earth
Earth Today: A Digital View of Our Planet

National Gallery of Art:
Oceans, Rivers, and Skies: Ansel Adams, Robert Adams, and Alfred Stieglitz

National Museum of Natural History:
Dig It! The Secrets of Soil
Orchids through Darwin’s Eyes
The Sant Ocean Hall

Smithsonian American Art Museum:
Accommodating Nature: The Photographs of Frank Gohlke
George Catlin's Indian Gallery
1934: A New Deal for Artists

And, if you’re not in the area to make the trip downtown, many of these exhibits and all of these museums have online collections and exhibitions.

*The museums are free, but you’ll probably want a Metrorail fare card to get to and from the Mall. And, remember to pack a lunch to keep costs down.

Image source: Smithsonian Museum of American Art