This is sort of a long-shot, but once I was elk hunting in New Mexico, and I stopped to eat some lunch in an area that was pretty dense with trees (well, not by East Coast standards, but pretty dense for New Mexico). Later, as I was walking around I decided to take a practice shot at a pine cone. I reached into my coat pocket for my shooting glove, but it wasn't there. I figured I must have pulled it out when I sat down on a log to eat lunch, but I had no idea how to find my way back to that exact spot. Then I remembered that I had turned on my GPS there to find out where I was. Although I hadn't created a way point, because I didn't think I would need to come back there, the GPS always makes a dot on the map whenever it is turned on. So I looked on the GPS map to find that one dot, and when I found it I navigated back to it and sure enough there was my shooting glove on the log.
Hope you find your phone!