Death Cap 死帽蕈

Gully, Thank you for your information. Today I go back the places and found all the mushroom seem disappeared. (there was 5 pieces). So cannot verify the spore as your suggested method. I will try next time if have the chance to see it again.

Definitely not a true Parasol Mushroom (Macrolepiota procera), whether the gills are greenish or not.

There are many mushrooms which resemble the Parasol morphology. Broadly they are known as Lepiotoids, of which is this is certainly one. Lepiotoids are generally white spored mushrooms, with the exception of the toxic species Chlorophyllum molybdites who's spores are green.

At maturity the spores show up on the white gills of Chlorophyllum molybdites giving them a greenish tinge. I believe that is what we are seeing in your final picture where there is a darker colouration showing up which looks like a powder on the white gills. It is not clearly green, but subtle tones are not always easily seen in a photo.

Given that I know of no other mushroom which resembles this and has a spore colour other than white (spores are clearly not white in the photo), I think Chlorophyllum molybdites or it's Asian variety is very likely.

To be sure you could take a spore print - Chop the stem off the mushroom and leave it gill side down on some white paper or tinfoil over night. Spores will be left on the paper/foil and the colour will be easily distinguished.

I take photo of gill today, I think the gill is not green.

If the gills are not green, then it's the Parasol mushroom - Macrolepiota Procera.

I am not sure the gill is green or not. Cloudy today and I shoot at lowest position as possible on photo 2. Is there different if the gill is green not white?

Were the gills greenish?

This looks like The False Parasol Mushroom - Chlorophyllum molybdites, but I don't think that this grows in Hong Kong...