Many poets, such as Robert Frost, Wendell Berry, May Sarton, and Walt Whitman, are noted for their nature poetry, and you can find many anthologies of nature poems. One such anthology is Poetry for the Earth, edited by Sara Dunn and Alan Scholefield (New York: Ballantine Books, 1992).
The Writer's Digest website has suggestions on how to write a good poem and how to improve writing by Lawrence Ferlinghetti.
Xerces Society, in association with the Smithsonian Institute, Butterfly Gardening: Creating Summer Magic in Your Garden (San Francisco: Sierra Club Books, 1998).
A web search for "butterfly gardens" will turn up many results. Here are a couple: