Field mushroom (Agaricus arvensis) and puffball mushroom (Bovistella utriformis) showed the highest phenolic levels at 27.14–29.61 mg/g dry weight, strongly linked to antimicrobial and antioxidant effects. These compounds blocked bacterial growth at doses as low as 0.8–3.125 mg/mL against common pathogens and scavenged free radicals with antioxidant activity reaching ~4.9 mmol TE/g. The same phenolics also protect cells from oxidative damage by neutralizing reactive oxygen species and preventing DNA, protein, and lipid breakdown.