My name is Tom Reber, and I am the estate gardener at Meadowbrook Farm (Jenkintown)--I studied art (alt-process photography) for three years at Dickinson College before leaving to study horticulture at Longwood for two years.
Anyway, we did have a pink dandelion at Longwood in the research greenhouses while I was there. I am not completely sure where Tomasz (the plant curator) procured it, but he had been on a couple of plant expeditions to South America as well as the Balkans in the months before it showed up.
The sad part of the story is that the plant was deemed "not of display value," and sent to the compost. Tomasz did rescue it from that fate, but I don't know what happened to it--I saw it when he brought it back to his office; it had a certain charm of its own. I don't know if there are any pictures of it, but you can contact Tomasz at to see if he has any more information.
Good luck, and I hope everything works out!