Did I do this, or Nature?

Several years ago, as part of the conversion of what used to be sunny vegetable beds on the Gloucester property into shade-loving perennial beds, I bought and planted a Wood Poppy, which has thrived quite robustly, producing a profusion of pretty yellow flowers from mid-May through June. (I do, however, look at the height description on the label that came with it and think "18 inches, my ass!" -- quite literally, since the plant does come up to my butt, which is a good bit more than 18 inches off the ground.)

The other thing it does is reseed generously. There are getting to be significant numbers of them anywhere within about 20 feet of the original planting,which I am happy to let live as long as they're not in the way of things I'm actually trying to grow.

But now I've started noticing them along the local roadsides, some as far as half a mile away, and I wonder, are these all offspring of my plants? It's odd, because I'm not seeing them elsewhere on our lot.

The Wikipedia article linked to above says that they're native to the Northeast, so I'm not really worried about having loosed a plague on the land. And it's possible that they've been growing wild in the neighborhood for years, and I only started noticing them once I was able to recognize them.