Moss Soup
It's thick and slimy, but edible.
Overview
Moss Soup is an item that can be used as a green dye. Its documented use is entirely cosmetic: it does not have any tailoring use.
It can be submitted to the dye pots in Emily and Haley’s house at 2 Willow Lane to produce green dye, and it can also be used as a green dye in the Sewing Machine when a dyeable clothing item is placed in the feed. Outside of dyeing, no other use is listed here.
Official description
It's thick and slimy, but edible.