That's what I thought .. I opened it up and almost vomited it was so bad .. I left it open in hopes that the wind would clear out the scent .. didn't work .. so after two days of smelling this I decided to find out what died .. after moving a few pots around I noticed something red and spongy looking behind a pot .. when I moved the pot I found Clathrus columnatus - a Stinkhorn Fungus .. ewww!
After a bit of research I found out that they do pop up from time to time in cypress mulch that is kept moist .. that's what the floor of my temporary greenhouse is. I'm debating whether or not to shovel it up or let it do its thing.
