The first one is a dandelion-like weed - I have those too. They get very tall and then have a dandelion type flower. Much easier to pull than 'real' dandelions!

The second looks like a Joe Pye variation - sometimes the purple-leaved variety will throw all-green ones. I;m not positive on this one, though - could be a salvia seedling (like the pink annuals) or even a kind of tall ageratum.

Three is indeed poison ivy - or at least, that's what my PI seedlings look like.

Four looks a lot like a weed that comes up in my lawn sometimes, but I'm not sure about it - hope someone else will know.

I think 1 is wild lettuce, Lactuca sp., definitely a weed.
I agree that 2 could be Joe-Pye-Weed, but it might be other things. Is the stem square in cross-section?
I agree that 3 is PI along with a couple of red maple seedlings which at least here are sprouting in abundance after a bumper crops of the winged seed.
4 looks to me like Asiatic day flower, Commelina communis. It has blue flowers that are lovely, though small, but seeds around and has quite persistent roots. I fight an ongoing battle with this in the field behind the house.

OK - I'll go yank 1, 3 and 4. Though I'm wondering how those weed seeds got into my pots. I thoroughly emptied those pots last fall. Granted I didn't wash them - just brushed them out.

When the rain stops I'll go look at the stem of #2.

I have #2 all over the place. I'd like to know what they are too. I usually pull them in time, but I think when they bloom they look like small daisies.

Try posting on "name that plant?"

Looked at #2 again. Stem is round. And furry. Leaves are opposite.
When I google Joe Pye weed - leaves are similarly shaped, but placement is different.
Any other ideas? Or shall I try name that plant.

#2 looks very much like my Joe Pye weed. I'm not sure about furry stem, but the leaves on my plants are opposite one another as on your plant.

I have a volunteer mystery plant of my own (pictured) growing alongside a ditch in the front yard. It looks something like the plant that others helped me identify as Eupatorium, but that plant was blooming in autumn. Can this also be Eupatorium? Might it blossom all summer?

I really like it despite the fact that I normally am not a fan of white flowers. It's lacey-looking, like Queen Anne's lace or its relative Yarrow, (both of which I also like) but it is neither. Hmm I could end up with a white garden in spite of myself!

I think 2 is Boehmeria cylindrica/False Nettle.

I'm going to guess not poison ivy based on that picture. Looks like you have an opposite leaf pattern, but hard to say for sure on the angle of the picture.

http://www.purplebutterflies.com/photohints/poisonivy-identify.htm

no! I take that back, I think def. poison ivy:

http://www.purplebutterflies.com/photohints/poisonivy-photos.htm

I think you are exactly right, Jaynine. Photos of false nettle look identical to the plant in #2. It has a Joe Pye Weed look about it, but it's a dead ringer for False Nettle.

#2 does look like false nettle, but I also wanted to share the link to a similar looking weed, galinsoga. I think this is what I found in my garden.

http://awaytogarden.com/weed-id-galinsoga-and-commelina

Here is a link that might be useful: Galinsoga

Lalala- I think galinsoga may be it. Thanks. I'll be pulling it tomorrow.

Sped - I don't know what your white weed is, but I'm seeing it all along the roadsides these days. At least it's a pretty weed.

Spedigrees - You are right that your plant isn't Eupatorium.

The flowers and timing look right for Valeriana officinalis, but the leaves in the photo don't. However, I can't tell if the leaves I see are on the same plant as the flowers.