The United States Department of Agriculture (USDA) publishes an array of data across multiple sites, from their own specific site to the Economic Research Service (ERS), the National Agricultural Statistics Service (NASS), and the World Agricultural Outlook Board (WAOB), to name a few.
The data from the USDA supports not only agriculture, but a host of other disciplines, including biotechnology, business, economics, social work, sociology, urban planning, rural sociology and rural studies, international studies, and more. The links below are some examples of content.
The USA.gov site is a larger site which allows you to search the USDA site but also the Census bureau, the Dept. of Labor, and other government information. Depending on what information you need, this is another avenue. The GPO is the Government Printing Office, a comprehensive listing of what is published by them.