When a fungus encounters a particularly rich food source, what is the expected result?

Hyphae branch and stretch out quickly from their tips to shape a mycelium.

Hyphae is a long, spreading filamentous structure of an organism, oomycete, or actinobacterium. In most parasites, hyphae are the fundamental method of vegetative development and are altogether called a mycelium. Yeasts are unicellular organisms that don't develop as hyphae.