CEDAR RAPIDS — For retailers, holidays such as Memorial Day require a fair amount of thinking ahead. And stocking up.“It’s really that kind of grill-out, cook-out-type theme that people go with,” said Bryce Bortle, store operations manager at the Hy-Vee on Edgewood Road. Stores expect some items to be popular each year, including fresh fruit, condiments, corn on the cob, lawn chairs, lighter fluid and other grilling supplies.