[mdjlucan]

fand on how green roof

[mdjlucan]

this one as well

[mdjlucan]

all so this one

[mumofstig]

on that one ^ the leaves look a bit like celery   so I'm not sure what it is - sorry  

[Agatha]

re top 2 photos - I love the way pansies spread themselves around!  I had some coming up through cracks in the patio last year - the nearest 'planted' ones were about 15 feet away!

[Chrysalis]

The third could possibly be feverfew, just beginning to sprout....?

[arugula]

First one pansy, second viola, third ?...

[sunshineband]

Not feverfew Chrys -- I have quite a lot and the leaflets are more separated

Possibly celery as MoS said, but who lets celery go to seed??