These seed pods must have blown into our yard during the windy weather we've been having. They don't come from any of our trees and I don't recognize them. We first thought they were mushrooms, but then turned them over, saw the little stem and leaf, and realized they weren't attached the the ground. Zack broke one open and it's filled with tiny, dandelion-like seed fluff. I don't know how easy the scale is to discern here, but they are a little bigger than golf balls. They are also surprisingly light.
Now that I've been thinking about Vintage Chica's Summer Unschooling Project, I've started thinking we should pursue these little mysteries. Unschooling is the idea that kids (and everyone?) learn best by pursuing interests in a more natural way. It's learning, but without traditional schooling methods. It is a type of homeschooling but Vintage Chica is working on it as a "summer school", a method of exploring and learning through the summer with her children (who attend public school). [There is a lot of unschooling information around. I hope I've represented it correctly, being new to the concept. But there are links on the site I mentioned above if you want to understand it better than I could explain it. I guess that was a disclaimer.]
Maybe we'll be able to track down what these are - hey, we might learn something!