This little head roughly 10cm in each dimension is flat on its underside. That means that it was probably a jar lid, likely for a canopic jar. Sadly it is one of the many ancient Egyptian objects which has no information on where it was found so we can’t know for sure what it is.
The Brooklyn Museum (where it now is, acc. no.: 87.78) dates it to the middle of the 12th Dynasty (c. 1850 BCE) on stylistic grounds – mostly based on the shape of the face and facial features. The museum also references the air of serenity that it has as a diagnostic feature.
See it on my photo site: https://photos.talesfromthetwolands.org/picture.php?/306/