Indian Pipe
We found these ghost-white plants on July 30, 2023. They were coming up in a stand of mixed tree types in our back yard (mostly alders, aspens, spruce, fir, and pines).
While these look like they should be some kind of mushroom, they are not. They are actually flowering plants that have become parasitic, and lost their chlorophyll. These are commonly called either Indian Pipes or Ghost Pipes, Monotropa_uniflora. They are in the Heather/Heath family, Ericaceae, and have proper flowers that look a bit like the bowl of a pipe.
While they are parasitic, they aren’t direct parasites of green plants. Their hosts are actually fungi in the Russulaceae family, which often set up a symbiotic relationship with trees. The fungi grow throughout the roots of the tree, and by decomposing plant matter and helping weather soild particles they mobilize nutrients for the tree to use. In return, the fungi receive food from the tree sap. It is pretty well-established that a lot of trees only grow poorly without their symbiotic fungi, so this is definitely a true symbiosis. But, the Indian Pipes don’t actually provide any benefit for the trees. They just tie into the mycorrrhizae (filaments) of the fungi, and extract their nutrition straight from that. So they aren’t so much parasitizing the trees, as they are stealing food from the mouths of the fungi.
Since they are not dependent on sunlight, Indian Pipes can grow even in the deepest, darkest parts of a forest. The only reason they need to break through the surface at all, is so that they can get their flowers pollinated and spread their seeds. The flowers are mostly pollinated by bumblebees. Once the seeds ripen, they are extremely tiny and are spread by the wind. These plants can only grow when their hosts are present, so the seeds need to land in just the right spots in order to get established.
I only rarely see these, and always just a single clump, so they evidently are pretty finicky about where they will grow. I understand growing them on purpose is quite difficult, so you aren’t generally going to see these in anybody’s garden, except maybe by accident.