I believe it's when you are standing in front of the large tomb of the sailer that is gargling. There should be a trash can on your right up against the fence in the corner. It's on the ground in that area.Every time I'm at the Haunted Mansion, I've looked for this ring. After countless years of looking, I have yet to find it. I always thought it was by the exit, no wonder I never found it!
So to be more specific on it's location (so I can finally see it), is it located in the standby queue, the FP queue, where the two queues meet, or outside the gates?