I’m not exactly sure what you mean by “farmers market”. This could be different taggings in OSM, so best is you post the node number, or a link to OSM.
To understand what’s behind: OSM is a very free-format database. Every renderer – like openstreetmap.org or PE – will have to make a choice what is shown and what not. PE generally shows a lot more than openstreetmap.org (due to the possibility to switch on/off map layers, to keep the map readable).
So, if you refer to
shop=farm (as in example http://www.openstreetmap.org/node/2698586971): This is shown in openstreetmap.org as a dot, but it’s not shown in PE. (I already requested the feature to show ALL shop=xxx with a generic shop icon if xxx is not known to PE.)
=> In general, if a feature is important to you, request it here to be shown (by specifying the OSM-tagging scheme and giving some examples).. Sometimes, this is taken into account by the developpers, at least as a “Minor POI” (e.g. a POI having no proper icon.).