Obviously a kinda mushroom, appeared in clumps all around the edge if the lawn.

Question

Why and how do I get rid of them?

Answer 1

That is Coprinellus sect. micacei. They do not pose a threat. They are harmless and are eating some decaying wood, either left from a tree stump or buried underground. They are very beneficial to the area, and removing them will be difficult, since very very little of that mushrooms resides above the ground. The real body is in the ground and inside of the wood that it is consuming. What you are seeing is simply the reproductive organs if the mushroom.

If you did manage to rid your yard of it, it would leave your yard open to more dangerous pathogens such as those that destroy lawns and trees.

Still, should you choose to go that route most fungicides will do the trick. You may want to continue to keep them handy for what takes its place, though.