They are given vouchers that double their purchasing power, and the cost is subsidized by non-profits, state governments, and the federal government. In an article in the Feb/Mar issue of Virginia-based Flavor Magazine, writer and cookbook author Marian Burros describes the process.
Voucher and Tokens Allow Purchase of Produce
“With names like Boston Bounty Bucks, Fresh Checks, and Double Dollars, programs at a few farmers markets across the country-including some in the Capital foodshed-offer economically vulnerable people a deal they cannot refuse: as much as $20 worth of fresh fruits and vegetables for $10.”
The concept came from the reality that poor people often cannot afford the high quality produce that is usually sold in upscale markets, or in locations far from their homes, in remote areas. It works well with the explosion of farmer’s markets nationwide, showing up in various urban areas, and doing a brisk business with organic and local produce.