It is possibly yucca aloifolia, they have long stalks on top of tall plants. They may be hardy there, I'm not sure. If it is a low growing clump of yucca its possibly filamentosa they are very hardy. It could also be rostrata, recurvifolia, and maybe a few others. Their are so many diffrent types of yucca that it would be hard to tell exactly which one you have without a picture. most seem to have pretty long flower stalks, some longer than others. Filamentosa usually has stalks about 6' high on average. maybe you can do a search on the web under the the species names I provided and find the one you have.

Definitely not recurvifolia. Doesn't always do well in Maryland, from experience, and grows too fast to fit the description. Probably not rostrata, since the spikiness would probably have been mentioned.

Thank you both. I did some research and it appears to be filamentosa. It has the little curly hairs and the spikes can grow up to 12 feet tall according to one source. Of course it bloomed while we were away on vacation, so I missed most of the flowers!!!