I recommend you do the "Find Shards!" Funfest Mission. Go to the Entralink, then walk up to your Entree and press A. If it's not your first time, you have to do another mission first. To complete it, search for sparkling areas. You have to walk up to them and you'll obtain a Berry. Find 3 Berries or more and it's done! After that, new missions will be unlocked. Select "Find Shards!" and it will begin. This time, you'll obtain Shards from the sparkling areas.
Hope it helps ;)