Jew's ear

plural Jew's ears

1. A kind of edible fungus (Auricularia auricula-judae), growing on tree-trunks, formerly used for medicinal purposes.

   Hither also may be referr'd those multitudes and varieties of Mushroms, such as that, call'd Jews-ears, all sorts of gray and green Mosses, &c.

   1665, Robert Hooke, Micrographia, section XIX

   1 more example

   Over the hearth hang bunches of drying mushrooms, the thin, curling kind they call jew's-ears, which have grown on the elder trees since Judas hanged himself on one; this is the kind of lore he tells me, tempting my half-belief.

   1979, Angela Carter, ‘The Erl-King’, The Bloody Chamber, Vintage, published 2006, page 99