upstart

One who has suddenly gained wealth, power, or other prominence, but either has not received social acceptance or has become arrogant or presumptuous.

upstarts […]they call in reproach mushrooms

[S]he has no fair pretence of family or blood. She was nobody when he married her, barely the daughter of a gentleman; but ever since her being turned into a Churchill she has out-Churchill’d them all in high and mighty claims: but in herself, I assure you, she is an upstart.”

The meadow saffron.

Acting like a parvenu.

Self-important and presumptuous.

To rise suddenly, to spring

Th' Elfe therewith astownd, Upstarted lightly from his looser make, And his unready weapons gan in hand to take.

the beauteous beast Scared by the noise upstarted at our feet