Are you sure that they are mushroom? How is their form and colour?
Cold you give any photo?
Mushrooms are thousands of types and form, shapes, colour and so on are fondamental to identificate them. The most visible fungi are symbiont with a tree, of which absorbs nutrients through the roots, providing in exchange nutrients and immune help.
Sure you put some grass coming from the base of a tree, the hyphae of fungi were already inside the ground or tangled with the roots of grass.
The only real way to recognize the good mushrooms from poisonous mushrooms is to know them. Can not do otherwise. Therefore, you should call your Mycological Office of Health and show them your mushrooms and ask for identification. Do not trust the friend who says he knows everything, ask the experts.
Before remove it, try to identify it.
If the mushrooms are small and white, with thin stems, do not run the risk of eating them.
Langermania gigantea If they are round and white likes small balls, are "vescie" (typical of meadows), very good in the pan. Choose those perfectly white, inside and out. They are called mushrooms deer.

Coprinus disseminatus If they are small, with thin stems, and are made as semi-closed umbrella, of medium brown color, arranged in a scattered way, are "coprini", often highly poisonous.

(source: mushroomexpert.com)
agaricus campestris If they are of medium size, plump, white with pink strips under the hat, they are "champignons" (mushrooms of Paris), very good to eat.

I leave here because I'm making assumptions, in groups of fungi that grow in the meadow, in layers of grass that we do not know where they come from.
I could put a series of photos, but there are thousands of species, would take too much space throughout the site.
It's definitely better get you a picture (well, many photos from many points of view, depending on the size and stage of development, and also opening up the land and showing hyphae).
There are very poisonous fungi and wonderful mushrooms and fine. First of harvesting all, you'll want to see if you have valuable mushrooms in your garden. Or a danger.
If we prove they are poisonous (meanwhile keep away dogs and children) you can sprinkle the lawn with an antifungal, maybe periodically until final disinfection.
EDIT
- Amanita Caesaera, the Fungus of the Gods, which can cost up to 100 € up to the plate, are fungi of the meadows
amac http://ricetteleggere.com/blog/wp-content/uploads/2011/08/Amanita_caesarea.jpg
- Amanita crocea, are fungi of the meadows
- Amanitoide vaginata same
- Paris mushrooms same
And so many other.
Really you wouldn't wait a bit, and seeing if you have something of valuable? Then, why you plant fruit trees in your garden?
You NEVER can be poisoned by touching, and how taste it without touching?
(But you NEVER TASTE what you don't know !!)
But yes, mistakens identifications are dangerous. That's why here in Italy, when we aren't sure, we have Mycological Centers in the Offices of Health that can help.
I know mushrooms perfectly. But always I ask a conferme to them, just for more surety.
But I do not ever deny the casual pleasure to find something good. Or just nice. Or just new. And, as an amateur herbalist, to make new discoveries for the sheer pleasure of discovering.
And I would never tell anyone to throw it all away, without even trying to understand. Our mind needs to discoveries, and understand, and learn. Not to become merely passive players in the rules that we receive.
I don't want be rude, just that is what I think.
=)