Vegetable seedlings are most often attacked by slugs or snails - I'd definitely bait for those and often. Cutworms and other insect larvae can do a lot of damage as well. You can fashion cardboard collars out of paper towel or toilet paper rolls or sprinkle cornmeal mixed with Dipel (granular Bt) around the plants. Diatomaceous earth is also effective sprinkled around the seedlings but again, these granular-type controls will need to be reapplied frequently during rainy periods. Slugs, snails, cutworms and various other leaf-munching creatures all tend to be nocturnal so chances are you won't see them during the daylight hours.....just the remnants of their feasting.

I think you might be right... I just googled mustard greens, and found a pic that looks like it. DH refuses to eat it, at any point. Says 'what if it's poisonous?'. Me? I tend to be adventurous... When I planted the seeds, I did so in a 4" space, and no other weeds (at least, not that big!) have popped up anywhere throughout the garden. So it must be a stray seed from the packet as I'd mentioned earlier. Would you harvest and eat it, not knowing for sure? Or wait and see if mustard seeds come of it?

Thank you to all who responded. carolb_w_fl_coastal_9b, on a cross-post (and I do apologize for having posted this all round GW/Houzz - I did try to keep this thread contained) posted a photo of Holland Greens, and it's pretty much identical. Still, I've decided not to try to cook it and eat it as I prefer not to take the risk. Shame, too. ken_adrian - I'd thought of that possibility. We'd prepped the soil well but did not sterilized it. And I do believe it's a rogue seedling, but perhaps more from the seed packet, because it grew in the same place with the same rate as the other's I'd planted. LOL! Well, we'll see if they overwinter, huh? Truthfully, I spoke with a couple locals who said carrots would be sweeter grown in the winter here in Eastern Tennessee, and if I wanted broccoli, to plant that late fall as well as summer broccoli never did well here for them but winter broccoli was wonderful. Winter harvest... I'm new to this! The brussel sprouts were a whim so again, we'll see. Just covered our veggies as it's supposed to be 34 F or less tonight. Pouring rain the last 2 days, so mucking about with plastic in the mud and wind was not fun! The things we do.... : ) windberry, no, no bulb. If it does anything other than continue to grow as shown above, I'll post a pic. I sure was wishing for an unusual broccoli or turnip. Eh...

It really is pretty isn't it? I used to be able to trick my kid into eating cauliflower with the purple kind. He thought it was "cool" so he'd eat it. Totally worth the extra money.