Piney Woods Lily

I was happy that these pretty purple flowers have been making an appearance again this year. I first noticed them a couple of years ago when two or three of them showed up. But this year there have been at least a dozen or more. They usually pop up one day and then are gone the next. So I have to be quick to take a photo of them. I think they're called Piney Woods Lily.  I'm trying to remember where they are have been so I can dig them up later and plant them all together.