But I didn't... this is just one onion.
I found it in the chicken coop months ago, it had produced some shoots just sitting there so I popped it into the ground in amongst everything else. I wasn't sure what to expect, I am remarkably devoid of onion experience.
Now that I come to think of it, I really have no idea how they grow. From a seed? Fairy dust?
I do know though that if you put them in the ground they seem to multiply... and the stems smell yummy too.