Stropharia aeruginosa, commonly known as the verdigris agaric. At first it is a vivid blue/green, and very glutinous (slimy), with a sprinkling of white veil remnants around the edge. The colour in the gluten fades, or is washed off as it matures, and it becomes yellow ocher, sometimes in patches, but mostly at the centre. Finally, it will lose the blue-green coloration completely