Try looking at this web site. It has a lot of references to people "seeing" things in trees, trunks, pizza pans, etc.
http://8minutesold.com/?p=55
Peace!
-Kevin
Pareidolia & Apophenia
Links don't work to the articles or pictures. This just goes to show you that people see all kinds of stuff when they look at stuff. I used to lay on the grass and watch the clouds turn into different things. Light, wind, rain, snow AND DRUGS or alcohol can have a bid bearing on what we see or think we see. I have some pain roller marks in the ceiling of my garage and one looks like Our Lady and one looks like and angel. Well, I know it is just paint but I could make a big hoorah about it and say that it is there because it is a miracle. No, it is there because hubby was careless with the roller on the end of the pole. 
Devotion to the souls in Purgatory contains in itself all the works of mercy, which supernaturalized by a spirit of faith, should merit us Heaven. de Sales