An unpollinated Trillium will also eventually turn color. Pollination may speed up the process. By the way, my Trilliums don't set much seed unless I hand-pollinate them. The pollinating plant must not be a clone of the plant to be pollinated. This is typical of many Lily family plants.

Thanks lilydude. Do you know, botanically, why the color change from white to dark pink? Just curious.
I've heard from several different people (who might just be passing around the same faulty? garden lore) that certain flowers change color to indicate having been pollinated, kind of like wearing a wedding ring or changing the ear you wear your flower on : -). Is this completely false? If so, too bad. I kind of like the idea.