It may be difficult to discern the beginning of fall around here, but the unofficial marker for many is the return of the West Palm Beach GreenMarket. Currently No. 2 on the annual list for America’s “Best Farmers Market” in USA Today’s 10Best Readers’ Choice Poll (it was No. 1 the three previous years), the 30th edition of the West Palm Beach GreenMarket is back on Saturday from 9 a.m.