What Kind of Weed is This?

I have a weed growing in my lawn. It is quite soft when it is green. I pops up in early spring and by end of May is dying. When it starts to die, it has many, many stickers. I have researched until my eyes hurt and have not found out what kind of weed this is. The dogs don't even want to walk on it. It grows close to the ground and spreads.

By Mary C.