No.2 looks like Black Mustard (
Brassica nigra)
The third plant is definitely a
Conyza fleabane, and they can be quite tricky from photos. However, on yours the stem is very sparsely hairy and the bracts (green bits around the flower) appear completely hairless - that'd make it
Canadian Fleabane (
Conyza canadensis).
C. sumatrensis has the bracts noticeably hairy and the stem pubescent. The other increasing species these days is Bilbao Fleabane,
C. bilbaoana, which has appeared everywhere this year on my Bristol patch; it has hairless bracts like your one, but the stems are very stiffly pubescent.
I'll try to post up some photos when I get chance to resize them
