Nodding trilliums challenge the photographer. You either contort yourself, and maybe dig a hole for the camera, or you contort the plant. I will confess I usually split the difference. It's important to get under the flower enough to show the pistil and stamens. In the red image on the wildflower page, I was down on the ground, but I also pushed the plant back a little. Lighting is also a challenge. In this case the image was backlit by the sun, and photoshopped a bit to reduce contrast.
As I said on the wildflower page, color and nodding are not reliable keys for this plant. Here we see a white one. Color can vary from white to deep red. The intermediate forms are very pretty. In MIchigan, the flowers almost always nod. Red trilliums (T. erectum) also sometimes do. As one goes south, by the time you reach Kentucky, T. flexipes flowers are almost always erect, and more often white. Farther complicating the issue is the species' promiscuity. It freely hybridizes with several other species. With such plants, the best hope may be that the parents are nearby to provide clues and comparisons. The reddish ovary in the white petal example here could owe that color to some T. erectum genes. But probably not because red trillium isn't known in the county. So I would put this one down to individual variation. Yet another complication. There are many among the more than 50 species on the continent.