Yes they can be used.I would put the heads out of the sun in a dry place.They may want to sprout??? Maybe they were wet? when you pulled them out.In any case garlic freezes well and is actually easier to use from frozen.

Thanks scarleta! Yes, it's possible they were a little wet or they might have gotten wet in that brief thunder storm we had last week. My garlic was all hanging in our covered deck, but the storm blew a little rain onto them.
So you're saying we should freeze the green ones or use them immediately?

"So you're saying we should freeze the green ones or use them immediately?"
Yes you are correct.
If you have more garlic it can all be frozen. After I froze some last year I found that it is much easier to work with frozen cloves.So this year I shall freeze lots of them and plant less as they keep frozen really well not to mention how nice it is to work with them from frozen.

Do you peel the cloves before you freeze them?

ljpother: thanks for this question.Yesterday I was thinking that probably I should have explained how to do it.Your post just reminded me to do so.
Yes you divide garlic into individual cloves, peel them and then put them on on a tray so the cloves don't touch one another.Put in a freezer and when frozen ( or when you remember ) place them in a zip lock bag or container all together.That way you can just grab one or two as needed.
It really works well.