Solved What is this weed?

I have found a lot this weed in my garden. Are they harmful to the lawn? Should I remove them and how?

Please ignore the hails in the picture. I took the pictures just after a big hails.

Thank you very much.

 

Welcome to the forums.

The light green is a moss.
Caused by bad drainage...or in damp parts of UK.

You also have Cardamine hirsuta...which is impossible to get rid of.
It can flower and produce seed when only tiny...see pics below.

cardamine hirsuta - Google Search

Will leave further advice to others.

 

Thanks for your reply.

What's the effective way of get rid of moss? And prevent them from growing again?

I tried to remove those moss a few days ago and their roots isn't deep at all. Another question is how can I let my grass grow up again?

 

Why would you want to totally destroy what looks to be a glorious ecosystem in miniature ?
There will be millions of micro-organisms in your lawn totally dependant on the plants within . My 'lawn' is more weed , wildflower and moss than a monoculture of boring grass , which practically serves no purpose whatsoever !
I simply class it as a 'green-walkway' to more interesting parts of my garden .
There is a different attitude to 'weeds' nowadays , and people are realising and appreciating their benefits to wildlife in general .

 

I am concerning that those mosses will keep growing and kill the lawn.

 

I can appreciate your concern , but seeing the problem from a 'different tangent' shall we say , moss and other species could become your lawn .

 

Here our lawn is actually 70% moss.....it is green and I am actually happy to leave it alone.
We live in an area with solid boulders and stone right under the grass. It is very poorly drained.

Others in the area pay a fortune to have their lawn professionally cared for...they pay to air rate the grass. Scarify it. Feed it. Mow it regularly.
Yet the moss still comes back.
As far as I am concerned they are wasting their money.

 

Soil looks waterlogged. Bad drainage,clay soil ?
Stick a garden fork jnto it,wiggle it about,brush some sharp sand over it filling the fork holes .
Rake away the moss,reseed with the right seed. Let it grow before mowing it. Give it a seaweed feed in a few weeks.
Im presuming shading isnt the issue here.

 

Personally in my opinion its not a lawn if its full of weeds / moss ( I have high exceptions on how a lawn looks ), if you like moss and other plants in with your grass fair enough , I be looking into what WeeTam said if it were my lawn though.