Supplemental Security Income (SSI), a program administered by the federal Social Security Administration (SSA) that pays monthly benefits to low-income people with disabilities, is a separate program from the program that provides food stamps. Food stamps are provided under the federal Supplemental Nutrition Assistance Program (SNAP), which is administered by the United States Department of Agriculture (USDA). Like SSI eligibility, food stamp eligibility is also based on income and resources.
Although most people who receive SSI will be eligible for food stamps, each state is different. SNAP benefits are administered at the state level, and states differ regarding criteria for qualifying. For example, people who live in California and are receiving SSI are not eligible to receive food stamps because California already includes extra money on the monthly SSI federal payments to be used for food.
Some states have a combined application system, where you will automatically be enrolled in SNAP if you are eligible when you apply for SSI -- if you are the only one in your household applying for or receiving SSI. (If there are other members of your household on SSI, a food stamps representative at your local Social Security office should help you fill out a separate application for food stamps.)
Because of these state-by-state differences, you should contact your local SNAP office or Social Security office to see if you are eligible and to fill out an application. You can find an interactive map with local SNAP office locations at the USDA website (http://www.fns.usda.gov/snap/outreach/map.htm).