Good timing. I've been thinking about this too. Chickweed was a pioneer staple for early spring greens; very tasty and very early, though larger amounts have laxative properties.

But also consider: Quackgrass. The invasive bane of farmers and gardeners.

Apparently edible. My dogs and cats seek out fresh green shoots and chew them up. I put a spadeful in a plant pot to give them some spring tonic. Cattle and horses graze it too.

It's said to be dieuretic, so watch the amounts.

Reports indicate the roots can be ground into flour and the seeds are edible (watch for purple tips, though, I've seen hints of ergot fungus).

You have to be mighty determined to kill this stuff. And even then, your victory will be temporary.

Anyway, I'll never run out. (I'm trying to look on the bright side.)

http://journeytoforever.org/edu_quackgrass.html

http://www.eattheweeds.com/quack-grass/