Rural Housing Direct Loans are loans that are directly funded by the Government.   These loans are available for low- and very low-income households to obtain homeownership.  Applicants may obtain 100% financing to purchase an existing dwelling, purchase a site and construct a dwelling, or purchase newly constructed dwellings located in rural areas.  Mortgage payments are based on the household's adjusted income.  These loans are commonly referred to as Section 502 Direct Loans.

http://www.rurdev.usda.gov/HAD-Direct_Housing_Loans.html