I don't know the answer to your specific question but you can tell if a bulb is NOT an onion by its lack of onion smell.

It 'could' be any number of things, including wild onion, wild garlic, or even a combination of numerous thug bulbs.

They 'could even be Ornithogalum Umbellatum, an 'introduced' bulb that is very invasive. My property is infested with it, and I spend from mid Feb through early May, on my hands and knees digging the bulbs out, while the foliage is visible. It's nearly impossible to do without the foliage visible.

There's the possibility too that they are Muscari, ie Grape Hyacinths. Under the right conditions, they are heavy reseeders.

Once the temperatures cool this fall, the foliage 'might' emerge. If it emerges then, you might have a possibility of identifying it then, and getting to spend a lot of time digging, trying to eradicate it. Onions, garlic, and muscari all put up foliage in the fall.

Might you have a picture of some of the bulbs? Wild onions are rather tall (elongated) bulbs, whereas the Ornithogalum are more rounded. Have you tried crushing any of the bulbs to see if they smell like onions or garlic?

Whatever it is, I wish you luck in getting it gone.

Here is a link that might be useful: USDA range for Ornithogalum Umbellatum

Another possible is Ipheion - which also smells 'onion-y'.

If you put one of your NOID (no ID) bulbs between a rock and a hard place and squish it you can settle the matter quite quickly.

BTW - Ipheion has flat leaves, quite narrow, and starry flowers, either white or pale blue, which have darker stripes running down the middle of each petal on the back.

Another likely culprit is Muscari which tends to form clumps of bulblets around a bigger bulb. If you are fond of Muscari, simply remove as many of the bulblets as you can and replant the bigger bulbs. Do not wage war on them until you've seen which varieties you've inherited. There are some rather nice doubles and whites many gardeners would be glad to have.

If it is Muscari - expect the leaves to be emerging (they look like skinny scallions) about now - in the summer heat.

The next rapid multiplier is bluebells - whichever name the botanists have for them at present. However - only some of the bulbs will be round. Others will be long and odd-shaped.

I strongly recommend you dig any of them up for disposal while they are in full growth and before they set seed. (Mid to late spring) That way you can usually catch them before they've started forming any new bulblets. Any that have formed will still be clinging to the adult bulb. Later, when summer is in and growth has stopped, if you move them, the young bulbs simply drop off and disappear into the dirt. (They're not silly!) ;-)))

Oh Noes.... this worries me about Ornithogalum Umbellatum as I planted some (yes on purpose!) in my yard last fall and I enjoyed their flowers late spring this year.

I have battled too many invasive plants to feel very comfortable about this bulb now that I've read chemocurl's post. I was about to plant even more of them as they were very cute. I do know how quickly *cute* can get out of hand though!

This quote from wikipedia gave me a chuckle, imagining the bulbs *escaping* cultivation!

In North America, it has escaped its cultivation as a garden ornamental and can be found in many areas.[2]

this worries me about Ornithogalum Umbellatum as I planted some (yes on purpose!) in my yard last fall and I enjoyed their flowers late spring this year.
YIKES! I'd suggest you look for the foliage to start to emerge in mid-late Feb in your zone, and on your hands and knees, dig out the bulb and the surrounding soil. They 'must' be dug, as trying to pull them will just leave any and all of the smaller side bulbs.

I have little actual grass, I think because of the star of beth, but the pic below shows the clumps of dark green star of beth foliage in the yard, while the grass and yard weeds are still dormant.

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Looking across the front yard (pic below)
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