plum

Any of several trees producing edible oval fruit having a smooth skin and a single hard stone.

A highly desirable position or assignment.

“a political plum”

Any of numerous varieties of small to medium-sized round or oval fruit having a smooth skin and a single pit.

Exactly.

“fell plumb in the middle of the puddle”

Completely; used as intensifiers.

“I'm plumb (or plum) tuckered out”