If they are a really deep green with a rounded 'top', that might be the 'surprise lilies'. They put out greenery in the spring, then die down, and long about August, boom, you've got these beautiful pink lilies on a long stalk. Hope those made it, they are really pretty in the hot days of August!
That sounds like it...I spotted one at least. I kept some in the garage over the winter. Perhaps I should pot them up today.