Image by bradipo, used under a CC license.
The Green Man shows up all over medieval European architecture (although this one is in Central Illinois). He’s a sort of vegetable deity, associated with rain and fertility. Mythical vegetable gods can be found everywhere from Mexico to Tibet.
Stories of male gods who go through a cycle of death and rebirth (think Odin, Osiris, or Jesus) are also associated with the Green Man, who follows the changing seasons. Oddly, lots of Christian churches are adorned with this pagan deity. Chalk it up to the early church appropriating local folklore to grease the conversion skids.
I myself am in no danger of any sort of spiritual conversion. I just think the Green Man looks cool. We’re getting a lot of rain around here lately, and those ultra-vibrant, early spring greens are just coming on. You can practically hear the flowers breaking free of the damp earth. It’s Green Man weather!
Edit: And bringing Green Man into the modern world, there’s this.