Umbonate:
An umbo is a softly curved bump in a flat cap. A cap with an umbo is said to be umbonate, as in the two larger mushrooms at the left [omitted]. The two small mushrooms at the right [omitted] have a central bump on a convex pileus, and are said to be campanulate, or bell-shaped. In this case, the bump is usually not considered a separate feature. [The Journal of Wild Mushrooming]
Noted in this video from gingerpale:
Don’t take Literally too literally.
