Stats for Full Set

Weight: 12.1
Damage Negation:
Physical 13.1 Strike 15.3 Slash 5.7 Pierce 11.4
Magic 28.9 Fire 11.4 Lightning 27.9 Holy 28.2
Resistance:
Immunity 243 Robustness 57 Focus 215 Vitality 181 Poise 2

Where to Find the Mushroom Set

You can find it in the Seethewater Cave dungeon in Mt Gelmir. Once you jump down the poisonous waterfall, head southwest and follow the tunnels until you reach a room with several enemies and a Giant Miranda Sprout.