Hi Buttoni - check out Platycodon, balloon flowers - they have big fleshy roots... it's been years since I grew them but I think it's a possibility. This Blog post has lots of photos and if you scroll down there's one image of young emerging plants.

Annie

The leaves look a bit like Blue porter weed. Did you happen to have one planted anywhere in the yard where the tiny seeds could blow over to the herb bed?

Some things you just have to wait until they flower. I've been waiting on a certain plant to do that for about five years. Since it doesn't get in the way of anything then wait I will.

Thank you, Annie, for that link! The shoots in their bottom photo look EXACTLY like these things when they sprouted up. Would you believe that since I posted this, the 3"-5" shoots are now 15-17" tall? No blooms of any kind yet though. But I vaguely recall planting a little 4" pot of balloon flowers (that later died off in our heat and the shady spot they were in) that was situated some 10' away from where these have cropped up, so maybe seeds off those were blown to this new location. I'm leaving it where it is for now and just enjoying it bolt higher and higher. :)

@Roselee, I've never had any Blue Porter planted in my yard. But I have had some surprises sprout up that the master gardener that lived here before me might have had planted. It does look similar, but I think the balloon flower Annie mentioned is exactly what I've got, and I KNOW I had some of those situated nearby this spot last year.

Now I'm jealous! Maybe I'll try to grow balloon flowers again- they were one of my favorites.

I got this plant just because they are fun to watch bloom poofed up, and then they open up.