It might be Agave americana mediopicta alba although there was a similar looking plant that was not an agave (it had softer leaves) that they were selling at Lowes this spring. There are other striped 'century plants', too.

Here is a link that might be useful: Agave americana mediopicta alba

Patty remembered the name of the other plant I was trying to think of: Furcraea. It is a member of the agave family. Click on 'visit page' on the link below for more information.

Here is a link that might be useful: Furcraea

Roselee - I posted on the Plant I.D forum and they came up with Furcraea too, so it sounds like that's what it is. I found it at San Marcos Growers and it says it can get to 5 ft tall and 8 ft wide with a 25 ft flower stalk. Yikes! I love the looks of this plant, but that's big.

It is a beautiful plant but my goodness -- that is huge! I was very tempted when Lowes had it, but was afraid it would not be hardy in my zone.