They are flagged NO VALUE precisely to prevent them from being dumped on vendors because that would make it more difficult for artisans to get supplies. You'll need to sell them to players, and you probably won't find any buyers because just about everyone is working hard to get their harvesting skills up, which means that everyone's got plenty of whatever you're trying to unload.
Your best bet would be to put them on the market at 5cp each or something and hope for the best. You might get lucky.
You know, there are trader and crafter chat channels that reach worldwide, not to mention the auction channel for the zone you're in. If you ask around from time to time, you might actually find somebody willing to buy them.
You probably won't, though, as everyone that uses harvested items is harvesting like mad to get their skills up right now.