DAVENPORT, Iowa -- The lush red strawberries caught the attention of Rachel Patrick, a mother of five shopping at a farmers market along the Mississippi River here. She selected two cartons and ignited a little-noticed chain reaction that is an important part of President Barack Obama's economic stimulus plan.

Ms. Patrick handed a plastic card loaded with her monthly food-stamp allocation to farmer Ed Kraklio Jr., who swiped it through his electronic reader. Mr. Kraklio now regularly takes in several hundred dollars a month...