Yes, it is garlic, and looks like pretty nice garlic at that. You can plant the bulbils (the little ones on the right), and they will form full-sized heads in two growing seasons, large single cloves next year. You can also dig the large heads and separate and replant individual cloves.

That's these were inside the bulb that was underground. Can I plant and or cook with them?

Those sure look an awful lot like egyptian, or "walking" onions to me. In fact I'm like 99% sure. Also, those leaves on the left of the picture look like sweet potato leaves.

If it were garlic, it would really smell like garlic. I think it's a multiplier. You can go ahead and replant the topsets now, and they will grow into scallions in time for fall harvest.

When I pull my mother plants (your big bulb there), I cure them like onions and then use the "shallots" until they are gone. Each bulb will have the remains of the flower stalk and a one or two nice shallots.

Smell a lot like garlic after I started opening one. The leafs that are on the left are a small vine that was entangled in the plant. I also found one that looks like a small garlic.