What are they and how do they propagate?

They're mostly concentrated in one area of the lawn. Easy to pull, but they keep coming up and gets taller than the grass quickly. I see them in my neighbor's flower bed, and around the neighborhood. My local VA tech extension couldn't say what they are.

The picture below makes them look darker green, but they are light green, so they are easy to spot in the lawn (in addition to being more upright and taller), with reddish color around the stem.