It looks like a yucca. Here is a link that might be useful: yucca

Oh yes, I'd love to have one too, thorns and all. I have some that are worse, but the flower is so wonderful it is worth it. I mean roses have thorns too. ;o) Cliff, are you going to Veronika's swap? I can bring you a fun sun bromeliad to trade for a pup of that. Let's talk, send me an email. ;o)

You have Helianthus giganteus in your area, and it seems to be a good match. Those plants have leaves that are sessile to short-petiolate, with mostly entire margins, and they grow to 400 cm (a bit more than 13 feet) tall.

It looks a lot like my Fockea edulis, and I got mine from the Philadelphia Flower Show too, I think. The booth that used to sell all those interesting plants has been gone for a couple years. I miss it.