Nidula is a genus of fungi in the family Agaricaceae. Their fruit bodies resemble tiny egg-filled birds' nests, from which they derive their common name "bird's nest fungi". Originally described in 1902, the genus differs from the related genera Cyathus and Crucibulum by the absence of a cord that attaches the eggs to the inside of the fruit body. The life cycle of this genus allows it to reproduce both sexually, with meiosis, and asexually via spores. Species in this genus produce a number of bioactive compounds, including 4-(p-hydroxyphenyl)-2-butanone, a major component of raspberry flavor and insect attractor used in pesticides.