See: Monsanto's Sordid History from the Center for Food Safety
GMWatch has compiled information on how Monsanto is trying to force-feed GE food to the world.
"A Monsanto History" (2004) was published by CropChoice.org
The Organic Consumers Association's Monsanto page also has lots of Monsanto history.
The ETC Group publishes reports on the global seed oligopoly, including this one (2005).
Rachel's Environment and Health Weekly has information about Monsanto and dioxin, Agent Orange, PCBs, and BGH, as well as the precautionary principle. (use their search engine to find relevant issues)
"A Checkered History," by Brian Tokar (The Ecologist, 1998)
Seeds of Deception by Jeffrey M. Smith
Food, Inc. by Peter Pringle (2003)
Fatal Harvest by Andrew Kimbrell (ed.)
Hungry Corporations by Helena Paul and Ricarda Steinbrecher .