I noticed this little surprize blooming in a clump of fall asters in my back border this morning. The wider leaves you can see in the picture belong to the fall asters, but the very skinny ones belong to my Mystery Plant.
I wonder if they are some kind of Puschkinia. The leaves and flower shape are the same, but I've never heard of ones that are this colour. And the other Puschkinias are long since past blooming in my garden.
Update: Thanks to Pam, who has a lovely garden blog at http://pamsenglishcottagegarden.blogspot.com/, who looked up Puschkinias and found out that they do, indeed, come in this colour, I'm sure that's what it is.
It is exactly the same shape and size as the striped ones. Thanks Pam!