Part of being a scientist is about being observant of one's surroundings, so from time-to-time I may include things out of the realm of geology.
Photography of mushrooms (and things related) has been a hobby of mine for a while. When I walked into our backyard a few days ago, I noticed this "yellow stuff" on some lichen-encrusted tree limbs on the ground.
Checking one of my reference books, I found a photo of "Witches Butter", another name for which is yellow brain fungus. Supposedly it is edible and I believe I saw some reference to Witches Butter Soup. But of course, don't use my identifications as an OK to go ahead and eat anything that looks like this.
The name sounds like something out of a Harry Potter movie, perhaps a potion ingredient.