Websites:

FAOSTAT
Statistics from the Food and Agriculture Organization of the United Nations include trade statistics.

Foreign Agricultural Trade of the United States
Data from the U.S. Department of Agriculture Economic Research Service.

Institute for Agriculture and Trade Policy
The IATP looks at the impact of global trade agreements on the U.S. farming community and U.S. policy.

International Agricultural Trade Research Consortium
With a membership of over 200 international agricultural economists, this research association publishes papers that are available through this website.

National Agricultural Law Center: International Agricultural Trade
Extensive links to U.S. and international agreements, regulations, and case law.