Can organic foods be reliably identified at farmers market?

GENERALLY YES: There are strict standards for food to be officially certified "organic" and, at least where i live in santa cruz, ca a grower can not represent their foods as being organic unless they have been certified as so. I imagine that this is the case at other farmers markets across the country. See http://www.Usda.Gov/wps/portal/usda/usdahome?Navid=organic_certificatio.

Yes: If the food is locally grown, look for evidence of certification (if they've got it, they'll show it!) and get to know the farmer, too. Ask about the produce, their farming practices, how long they've been growing organically.