i never got a tough meat from mushroom...nor a broken bone and im pretty sure they dont drop it either
summoned beast leather is also dropped by slimes
i got some from them, the regular ones lol
there are three main types of monsters from what i see, humanoids/beasts/magical - of course there are exceptions like undead and such
beasts drops leather, bones, meat
magical drops stones, dust, souls
humanoids drops signs (vanished signs and higher versions of vanished signs)
not too sure for humanoids but they also either drop the same things as magical
every monster can drop potion, accessory, weapon, armor, etc
so instead of having a list of what item each monster drops, why not just do their type, the item level they drop, and special drops they give
item level are different levels of items, tough meat is level 1, tender meat is level 2, chewy meat is level 3... etc etc