the first thing that comes to mind are snow drops
Galanthus nivalis

Here is a link that might be useful: google images - Galanthus nivalis

I would like to have snow-drops very much :o) but these don't grow in clumps and have never flowered. Looks like the snow-drops have flatter leaves also.

Looks like the leaves have a silvery stripe down the center: probably Ornithogalum nutans.

Snowdrops don't have tubular leaves. Muscari (grape hyacinths) do and they spread profusely like the picture.

I too am attempting to solve a mystery of grasslike plant with bulbs. This stuff it taking over my yard!!

Here is a link that might be useful: Pics of the unknown plant

Muscari?

My dad called it cocoa grass. I don't know why ( not its true name). We got it off a plow. It is very invasive and spread like wildfire. There is weed killer to kill it but you'll have to talk to a graden and ranch center and experts to learn how to apply. It will kill all things in that area. We had it even grow through our potatoes making quit a mess. We got rid of it by making a chicken fencing area around the site and the chickens took care of the problem. If one bulb is in tilled soil it will tranfer to that area and spread,
so be carefull.

How did this post, from several years ago get dredged back up? I'd be willing to bet money that this is Ornithogalum umbellatum, star of Bethlehem. A weed that I battle quite often.

Here is a link that might be useful: O. Umbellatum

O. umbellatum is what I was thinking of also, I inadvertantly posted the wrong species name.

Wild onion grass. Comes Up in tufts all over the place and spreads very quickly. Is listed as invasive!