Those are growing between my house and the grocery store.
Below is a close-up of some right across the alley from my back gate. You can see the stickers starting to form.
I have a page with notes on goatheads that I started a few years ago SandraDodd.com/goatheads.
After the frost, I'll go and gather a bunch up and photograph them and bring the image back here, I hope. (Feel free to remind me, anyone who comes by here in a few months, if I haven't done it.)
8/11 addition: I found a photo I had marked up a while back to show how sweet and innocent the goatheads look when they come up in the yard:
When we lived at our old house, Keith and I pulled every goathead we EVER saw—we would walk into the neighbors' yards to pull them (they certainly didn't mind) because we had little kids who liked to go barefooted. I would pull them at public parks. I would take gloves and a bag when we would go to the park. Now our kids know what the plants look like and I don't pull the goatheads out of the neighbor's yard. :-)
And here are two older photos of vacant-lot goatheads, when it was dry. One shows a single plant about a foot across. The other shows a couple of more older plants, probably four or five feet across all of that, and those seeds were ready to get me. One seed/sticker can create hundreds more. This wasn't a great camera so they're not totally clear, but honestly, goatheads are not used to being photographed at all, so these did pretty well.