I just noticed that a small portion of my yard suddenly seems to have hundreds of tiny beige mushroom looking thingys growing.

I've been here for 5 years and this is a first. However there was an old Sycamore tree there when we moved in which we cut down 4 years ago. Last year I used a new lawn patching product in this area to fill in where the tree was so it seems obvious that must have had something to do with it... though last year it was just nice new grass. The area is nice and sunny now that the Sycamore is gone so it's not a place I would expect to see funghi.

Any idea what this is or how to get rid of it?