This looks to me like pear-shaped puffball, Lycoperdon pyriforme. Usually when I see one of these I see quite a number of them, but this morning, I only spotted the one. These are good edibles when young and completely white inside. If you aren’t very familiar with small puffballs, slice one in half. It should be pure white all the way through. If it isn’t, beware. You might be looking at an immature amanita.
27th Street 
Now maybe, because you haven’t had much exposure to them. With a little experience, you gain confidence in your knowledge over time. If you were hunting butter beans instead of mushrooms, after you found them three or four times, you’d never mix them up with fava beans or pinto beans. True there are many species that are very difficult to identify, but we don’t lose sleep over those and concentrate on the basics.
I would find myself second-guessing whether or not the puffball was white all the way through, convinced I was killing the entire family.