Sauromatum venosum, aka Voodoo Lily. When I put it on the floor to photograph, Peppermint the cat came over to investigate. He took one sniff, and did a giant backward leap, his spine arched and his tail fluffed out in alarm.
Two closer looks at the inflorescence. That long dark spadix is normally straight, however being cramped in a small plastic bag for a few weeks caused it to twist. It looks serpentine and sinister, as something called Voodoo Lily should.
As intriguing as it looks, something that smells so bad that it discomfits the ever-intrepid Peppermint cannot stay indoors. Even a Crazy Plant Lady has limits. I potted it up and put it outside in the garage, since it was too early in the spring to put it outdoors. Though sources vary on how hardy it is, the far northwestern Chicago suburbs are definitely not in its range. The odor ceased after a day or so, and the flower began to fade. Later that month, I put it out on the porch.
This is what the plant looks like today:
...And I especially love the spotted petioles. (The dried husk hanging down on the left side of the pot in the top picture is the remains of the inflorescence.)
My plans are to enjoy the plant outdoors on my porch for the summer and then decide what to do with it in the fall. Oh, and the other bulbs I bought and forgot about were Liatris spicata for my outdoor garden beds. They were planted out later, and are doing fine.