The flower pot is in the first room to the left past the round room with the Seelie Guests and a surrounding hallway. It is to the left as you enter the room.
The Deviners can be found by leaving this room and making 2 left turns, putting you in another room with Deviners and Observers.
When attempting to complete this quest, do NOT kill the Seelie Observers that are in the same encounter as the Bixie Deviners. They are the only observers in the zone and you need them to complete the next quest "The Voice Speaks Again", otherwise you must all leave the zone and start clearing your way back again. Since I am a Coercer, I just mezzed them till the group members could pick up the next quest and return to the room. I had the quest from before... when we cleared the deviners and observers and learned too late that we needed the mobs we just killed, so I just stayed in the room to maintain mez.
After finishing the quest, the quest suggests you "look for a ring..", which is the rather large diamond ring on a table in the room where you started this quest (on the RIGHT side of the room, instead of left). The ring offers you "The Voice Speaks Again", which is to kill 2 Seelie Observers.