Mushrooms
I don't claim to know much about nature—I live in New York City by choice, after all—but I love discovering all of the strange and interesting things that manage to grow unattended in the woods. David and I recently went camping in the Catskills and before settling in for the night took a hike around the North/South lake. I always notice mushrooms because they're usually so adorable, but for some reason they seemed to be everywhere on this particular hike.
Sometimes I think people assume I know more about nature than I do, just because I grew up in Ohio. Sure, I had to do a leaf-identification project in school, but that doesn't mean I remember much beyond the difference between a maple and a ginko leaf. I do wish I knew more about properly identifying mushrooms—I love mushrooms so it would be pretty cool to be able to pluck part of my dinner right out of the woods. I knew people back in Ohio that swore by certain varieties but I've seen Into the Wild enough times that I'd probably never get to the point where I felt comfortable eating things I just found.
I have, however, heard of puffballs and we spent a great deal of time poking all of the ones around our campsite. I'm sure this isn't the best way to properly respect the beauty of nature, but it's just too satisfying to resist. It's also impossible to stop once you start, and we joked that we'd return next year to find the campsite closed due to an explosion in the mushroom population.