Not sure quite whether this comes under the gardening section but here goes:
One of our upstairs windows looks directly into the branches of a silver birch and it became evident that there was a bird's nest in the tree when all the leaves had fallen earlier this winter. Just a basic bird's nest. When I looked out earlier this week, I was astonished to see a bright yellow "thing" in the bird's nest (immediate thoughts of an egg disappeared, after all there should be a shell!!) But that's exactly what it looks like - it's still there.
Cue some deep thought .... and a bit of searching on the internet ..... and I think we can see a specimen of Leucocoprinus birnbaumii (a kind of fungus usually found in potted plants in the UK as it needs a warmer climate). I was a bit mystified, but we have had unseasonably warm weather, and it's been damp - so I reckon it's the right conditions.
Unless anyone can offer a better explanation .... (I can't get close to the nest as it's too high and too far from the window)