First one is Euphorbia, not sure which one. Seed weed. Second is a weed Artemisia. Needs out as the roots go down forever.
The weed is Fat Hen, not an artemesia. It's an annual and easy to pull up. It is also a sign of fertile soil. http://www.gardenersworld.com/how-to/solve-problems/fat-hen/
You can eat Fat Hen Be careful of the milky sap from the Euphorbia though, don't get it near your eyes
Known locally as Dungle Weed as it grows well where the dung heap has been. Or on skin. If I pick up a bundle of weeds containing Euphorbia I get red, wet blisters on the inside of my arms.