On a run in Portland’s Forest Park, I saw that someone had picked a trillium and hung it on a branch. When I looked closer, I could understand why. It has two sets of three leaves, and nine petals.
I took it home, cut off more of the stem at an angle and placed it in water. I couldn't find anything remotely like this online. The closest was the rare tetra variant. What do I do with this? Should it be preserved and studied?
This is a cool flower, but not so notable. There’s no need to preserve it. You can think of it as akin to a four-leaf clover. This happens with a lot of plants. It looks like your trillium duplicated an extra whorl of three petals and then wasn't quite sure whether to make sepals (green) or petals (white) with the last whorl.