So This Is Weird: A Garlic Mystery

Long time no type, eh?  A new term at school as started up and that coupled with some projects we're doing around the house and out-of-town guests meant no posting.

Thus, I come back after an almost 2 week hiatus with a mystery.  Hopefully someone on the internets can tell me what is up with this:

 

Obviously, this is garlic.  However, less obviously is that this garlic came from a place planted *last fall.*  Today I was doing the final clearing in the garden (that is another post, alas) and I noticed a square foot of leafy shoots come out of the ground where I harvested garlic in the spring.  I pull them up and it's garlic in various stages of maturation.  Some are starting to form heads (see bottom right corner of photo above) and others are just kind of starting out.

I'm pretty sure I harvested all the garlic out of that patch.  And, even if I didn't, it would have just been a clove or two and this was seriously an entire square full of growth.

Tell me oh wise readers: What is going on here?