For years, the food pantry in Crystal Lake, Ill., a bedroom community 50 miles west of Chicago, has catered to the suburban areas’ poor, homeless and unemployed. But Cate Williams, the head of the pantry, has noticed a striking change in the makeup of the needy in the past year or two. Some families that once pulled down six-figure incomes and drove flashy cars are now turning to the pantry for help. A few of them donated food and money to the pantry before their luck soured, according to Williams. “People will shyly say to me, ‘You know, I used...