It's colloquially called a Naked Lily or Surprise Lily. I think it is a type of Amaryllis.
Very pretty and lightly fragrant.
Enjoy!

Sorry, I was being lazy on my earlier post...
I looked it up for you. It's Lycoris squamigera, a member of the Amaryllis family. Some other common names are Resurrection Lily, Magic Lily, and Naked Lady.
They're very common around here. Unfortunately, I have none currently, but I loved them when I was a kid, and am always watching for them to pop up this time of year. They just appeared a couple of days ago. My kids have a great time scanning everyone's yards for Naked Pink Lilies each summer.

Actually, I believe it is one of the very few members of the Amaryllis family, also known as Belladonna. The large beautiful bulbs we buy in kits and plant up for indoor Christmas blooms are actually Hippeastrum, and not Amaryllis.

It could be lycoris albiflora aka white surprise lily. I've never seen them but would love to have some. Take them, find a nice place for them and if they get crowded after a few years and you don't want to spread them around your garden you can always trade them on GW. They are on so many people's trade list I've seen.

Here is a link that might be useful: White lycoris

There are two different plants that look like that. One is the Lycoris Squamagera and the other is the Belladonna Lily. I'm not sure what the differences are but you could google them and see what you find. I've been told that the ones in the south are Lycoris and the ones in the north are Belladonna.
Nancy

Please excuse my first post, even I can see what it is. I must have had a blank moment.

Nancy