That compares to a 7% same-store sales increase in the April-June period. Federal health officials first tied the diarrhea-causing outbreak to shredded iceberg lettuce served at Taco Bell restaurants in Indiana, Kentucky, Michigan, Ohio and West Virginia. Taco Bell removed shredded iceberg lettuce supplied by Taylor Farms from its U.S. restaurants on July 17. The following day, Taylor Farms recalled iceberg lettuce grown in central Mexico. The retail price of a pound of iceberg lettuce jumped nearly 20% between January and June of this year, according to government data.