My friend Tuckers sent me these photos from his trip to Mexico last week. His words: It’s called a Maya Drum Tree. I couldn’t find much about it online, but the trunk is hollow. And they planted them in the square at the pyramid and beat them to communicate with the town. When you hit it it does make a fairly loud "tonk."
Note the banged-up trunk, used for Mayan long-distance communication.
If you have a tree to share, send it my way: captiveww (at) yahoo (dot) com.