That looks like a Castor Bean seed. Were the pods prickly looking things?
Remy

That was my first thought as well but 2' sounds a little short for Castor Bean.

Here is a link that might be useful: Castor Bean

Yes, but since there are dwarf varieties of castor bean that only grow to 4 or 5' high, it could be from one of them. If the rest of the plant got wilted down from frost, you could have seed pods looking like they were at the top of the plant, but in actuality they were in the middle of the plant on the part of the stalk sturdy enough to still be standing.
Remy

Thanks for your responses. It may be castor bean or a related plant. The seed does look similar but not as smooth or polished-looking as the castor beans I'm used to. The plant was small - only 2' tall - and even though it was dead and droopy, I think I might have recognized the large leaves and shape of the castor bean plant. Unfortunately I didn't pay that much attention to the foliage because I didn't know I'd be trying to ID it later.
The seedpod (shown) is hairy and rough, but not spiky. Castor beans have 3 seeds per pod I think and that's what this had.
I'll plant the seeds in the spring and see what I get. Surprises are always fun!