20th century American poetry
Elizabeth Bishop
As with Stevens, there is a free online anthology of the key poems (though you should not necessarily trust the textual accuracy of editions of this kind: if you are going to write about one of these poets in an assessed essay, be sure to work with, or at least check, the proper print edition of their poems)
http://www.poemhunter.com/i/ebooks/pdf/elizabeth_bishop_2004_9.pdf
Read at least: ‘At the fishhouses’, ‘Florida’, ‘Giant Snail’, ‘Questions of travel’, ‘Sandpiper’, ‘Seascape’, ‘The Map’, ‘The Moose’
W. S. Merwin
Pdf anthology of 22 poems, all short, so please read them all:
http://www.poemhunter.com/i/ebooks/pdf/w_s_merwin_2004_9.pdf
Gary Snyder
The poems by Bishop and Merwin seem to me worth reading in the light of environment and ecology, but they are not explicit in their ecological allegiance. Gary Snyder, by contrast, sometimes produces poems of deliberate green polemic. Read his ‘Mother Earth: Her Whales’. The pdf anthology linked here is an interesting setting for it: a collection that has been self-consciously put together on the Morning Earth website as a series of examples of ‘poetry of deep connection’:
http://www.morning-earth.org/DE6103/POETRY/Deep%20Connect.pdf