Several small cities in rural Kansas will give you a land lot if you agree to fashion housing of at least 1,000 square feet on it. Mobile homes are welcome, and we'll be sure to wave as yours flies by in the next tornado. If one lot isn't large enough and you'd like to garden, the city of Marquette, Kansas would be pleased as punch to just give you a second lot adjacent to the first, also for free, says its website. These are developed lots, by the way -- they already have water, sewer and electricity.
There are opportunities in Nebraska, Iowa, Maine, and Michigan as well. Link -Thanks, Steven Johnson!