The pictures are awfully small, compare your plant to Conium maculatum, poison hemlock.

Here is a link that might be useful: Google image results

Yes, I believe that is it. Thank you!

Poison hemlock has reddish stalks, are the stalks tinted a red? It could also be Queen Anne's Lace or a Wild Carrot. I thought they were very similar.

What I can see this does not appear to grow like Queen Annes Lace although it is in the same "Umbelliferae" family along with the carrots, parsley, etc.
Poison Hemlock prefers to grow in wetter areas then Iris would like, along stream banks for example, and is much more common in Europe than in North America.

It is much bigger than any queen anne's lace I've ever seen. I will look for red on the stalk. It is coming out tommorrow, whatever it is!

We've had a lot of rain, and my yard can sometimes be too wet for many things--especially in late winter/early spring -- although this is in a spot that I've built up a few inches to improve drainage.

If it is Poison Hemlock, be careful, as all parts of the plant are poisonous. Wear gloves(many people forget this part)when digging/pulling it up, bag it up, don't burn it or compost it.

I have had lots of this plant. Have been unable to get a correct name but it does not have a carrot type taproot. It pulls easily when it is young. Round up just wilted it for a couple of days. Seeds stick together and are spread by everything. The only thing that has worked is to pull it while soil is wet or take a long knife and cut the plant well below the soil surface. If cut below where the roots come out the roots will die but it is like celery if you cut it above the roots new plants will come up.

It did have the characteristic red on the stalks--so I think it definitely was the poison hemlock. The stalks were hollow when I cut them, with liquid inside--I filled the stumps up with Ortho poison ivy killer in hopes that that will kill the plant without harming the iris. The iris are too closely planted to dig it up easily, and it did not pull out of the ground easily either.

Thanks about the warning about the toxicity, noinwi. I did put it in my compost pile, but it is just on top, so I can get it out and bag it.

I did show it to both of my neighbors with young children so they can watch for it--it looked so much like parsley when young.

Be glad it's not the Giant Hogweed.