Seek out the vendors in the city market and try to sell what you've harvested. I have hopes that you can help our faction's economy thrive, and earn yourself a place in our city to rest your head at night.
As of 31st July 2017, this particular task is a little buggy and might not register any gold earned from vendors. If this does happen, you can craft a Stone Sword (may trigger 'The Call of Adventure' task list), or reach level 8 respectively.
Otherwise, completion of the task itself is simple - the alchemist or mage vendors in your starting town should buy 100 Magic Shards for 50 Gold for a quick completion.