They look like single clove garlic bulbs which are known as "rounds".

Rodney

Agree, that's what my neglected garlic beds spit out this year.

They are rounds - plant them at the end of September, and they'll make very nice heads of garlic by next June, so long as reasonably good soil, not overcome by weeds, sufficient moisture, etc.!!

By any chance did you grow elephant garlic last year? Elephant garlic often forms rounds like that.

Very interesting; I didn't know garlic did that.

But why? Last year I planted cloves in the spring and nice heads developed. I have read about it on the internet, but it is confusing. Why did I get rounds this year?
One thing I read said that they come from bulbils? I didn't notice any last year, but I probably didn't watch the garlic that well...
Did they just selfseed, or selfplant, whatever.

The reason why is insufficient water and fertilizer and possibly too much competition from weeds.

They didn't self-seed.

Instead, the cloves you planted just plain failed to develop the multi-clove head you wanted because of the above reasons.

If you let your garlic "flower", then you may have self seeded little bulbs that formed in the flower - they produce round bulbs first year.