Trail running really is one of my favorite things in the world to do.
The crazy looking alien eggs are indeed a fungus. They're called giant puffballs. How appropriate! They grow in the late summer to early fall and can get up to 3 feet in diameter. They are also edible until they start to spore, which you can tell by cutting them open and seeing if they are turning brown on the inside. If they are pure white, you can eat them. The hubby and I tried some, and it tasted much like your standard grocery store white mushroom, only softer. Tracking them down again and giving them a try was a cool, geek-tastic, biology adventure!