While the permanent 28,000-sq.-ft. market is under construction—it’s scheduled to open in 2015—the Boston Public Market Association offers shoppers a preview in the form of seasonal farmers’ markets. One is on the Rose Kennedy Greenway side of the market building on Monday and Wednesday from 11am to 6pm, late May through the day before Thanksgiving. The association also runs the Dewey Square market, on the Rose Kennedy Greenway at Atlantic Avenue and Summer Street (T: Red Line to South Station). It operates from 11:30am to 6:30pm on Tuesday and Thursday from late May through late December.