Some onions I'd planted last year have decided to flower this summer. It hasn't taken long for the bees to find them.
These are ones meant to be eaten but I'll point out that some Alliums are sold as ornamental. There is a pink flowering variety in particular I've seen sell for $25 a plant. A complete waste of money in my opinion. These normal ones you eat cost about $5 for a pack of about 60. They take a year to flower but frankly people do that with bulbs anyhow.
After flowering you can cut the flower head off or let them go to seed. Harvest after the stem turns brown... I'm not sure if that means the tip, or the whole stalk. I'd assume the more you wait the fatter that bulb will get.
They're also the host plant to something. I've seen this caterpillar on lots of other plants and they seem to change color based on what plant they're on.