It may be Elephant garlic, but if so, it could be much larger. I've grown some over 6".

A few of my regular garlic varieties get close to 4" across.

This post was edited by madroneb on Tue, Jun 4, 13 at 0:25

It probably is Elephant garlic, which is actually a member of the leek species, and is pretty mild compared to most garlic. They are easy to grow if you already grow garlic. Just give them more space since the plants get bigger. 8-10" is plenty.

You could try planting cloves from the store, or they are available from a bunch of seed companies on the web.

I think the full-size plants, before they start forming bulbs, make a nice leek substitute, albeit with a little garlic overtone.

Here is a funny photo of some we harvested last year.
I planted a few hundred this season that are almost ready and this fall i'll be selling seed if you're interested.

-Mark

Those are huge elephant garlic, madroneb! Funny picture, too.