http://www.nass.usda.gov/Publications/Ag_Statistics/index.asp
This is a yearly publication covering agricultural production, supplies, consumption, facilities, costs, and returns.
Date range: 1936 to 2013
Below is a screenshot of the website:
Below is a screenshot of the types of information in the 2013 report:
http://www.agcensus.usda.gov/Publications/Historical_Publications/
This census is conducted every 5 years. Provides information at the national, state and county level. Collects information on all areas of farming and ranching operations.
Date range: 1840-2012
Below is a screenshot of the 1st page of the Table of Contents for the 2007 census:
