Mysterious coded messages at university library

"All the letters are in black, except for the leaf symbol which is green. The letter appears to be colour laser printed. The physical leaf is made of plastic and has two paint splotches on it - one red, one cyan. I'm not sure what the grey pillow-shaped object is supposed to be." - Mike Moffatt

Someone is leaving coded messages and items such as a plastic leaf with paint dots inside envelopes between the pages of books at Western University. “It’s completely baffling!” says assistant professor Mike Moffatt, who has been tracking the messages on his blog.