I brushed my wrist against it a little bit when I was cleaning this area. It caused me an itch and allergic reaction on the skin. There are two plants in the image, but I think I brushed against the big/darker green one. The location is San Francisco Bay area, California, USA).
Well both will be unpleasant to touch - the darker green one appears to be one of the thistles, and they have sharp barbs that are very uncomfortable and can cause skin irritation. I'm not sure what the paler green one is, it might be teasel, which does have prickles sticking out of the leaf surface like the one in your photo. Neither looks like anything you want to keep on growing, so if you decide to remove them, wear thick gloves.
like bamboo said the dark green one is a evil thistle. We have tons of those around here :( and they do hurt. But I am not aware of any reaction coming from them other then a prick from the 'thorns'.
I have a great guess that the light green one is "stinging nettle" which will give a burn/sting affect when touched. This is worse than thistle I think and both should be removed. While stinging nettle is a painful to touch plant it has some medical benefits. I will post link below. Also I am posting a link about why it stings. You may find these site interesting to read and learn from.
Use gloves to pull them out and don't let them seed!
Final note: I did look at pictures of stinging nettle and it looks fairly close. I see some saw like teeth on the edges. The leaf does look longer and pale but that may be the lack of sun and it trying to get that light. I posted a picture on here from one of the websites for others to see.