I cannot remember the proper name, but I refer to this as a "triple trillium" due to the multi-petals. This is a very unusual trillium which came from the edge of a hayfield when we lived near Orillia. That area was full of the "normal" white trilliums in the forests in spring. We had a patch of 3 and when we moved I brought this with us. There are no white trilliums growing naturally in this area, only red ones. I hoped this one would survive - this is its 13th year here!
Until 3 years ago, the 3 flowers never multiplied. This year there are 9 stems and flowers, however they are very small. The poor plant was one that was flattened in the snow recently, but surprisingly, has also survived, although a little floppy still. Isn't Mother Nature amazing!