What's this?

I direct sowed about 10 different things in this patch. I looked up pictures of seedlings of most of what I could remember planting. I'm pretty sure it's just some weed, but before I go pulling it all out...



It has a pretty long thick root.

Does it stink? Have a large taproot? There's a few weeds round here that resemble your photo, but considering I'm on the other side of the world, my weeds and your weeds are posssibly not the same...
I generally assume that if it grows like mad, it's not something I planted.