All trophies known by me:

alligator skin            train/study negate offhand penalty: +5%
bear skin                 train/study mangle: +10%
bear tooth                train/study bestial frenzy: +10%
bird feathers             train/study find weakness: +5%
buffalo hide              train/study impale: +5%
bull horns                train/study alertness: +7%
chimera's tail            train/study parry: +6%
claw of the sabretooth    train/study parry: +4%
enormous fishbone        train/study hunting: +10%
hardened mud              train/study stunned maneuvers: +10%
head of feline            train/study stunned maneuvers: +10%
head of the sloth         train/study camping: +5%
hide of a giraffe         train/study alertness: +5%
hide of a zebra           train/study alertness: +4%
hide of the feline        train/study discipline: +6%
hyena's head              train/study impale: +5%
leopard hide             train/study mangle: +10%
mane of the lion          train/study riposte: +10%
monkey skull              train/study stun: +6%
moose horns              train/study alertness: +6%
raccoon fur               train/study bestial frenzy: +10%
reindeer horns            train/study hunting: +10%
rhinoceros horn          train/study tumbling attack: +5%
scales of a drake         train/study find weakness: +5%
scales of a seamonster   train/study discipline: +7%
shark tooth               train/study discipline: +4%
snake scales             train/study shield bash: +10%
stinger of scorpion       train/study alertness: +8%
tail of a seamonster      train/study riposte: +10%
tail of a skunk           train/study negate offhand penalty: +3%
tentacle of squid         allows saddle on mount
tiger hide                train/study negate offhand penalty: +7%
tooth of the sabretooth   train/study mastery of mounted combat: +5%
tortoise shell            train/study bestial frenzy: +10%
tusk of the elephant      train/study combat riding: +5%
unicorn horn             train/study stun: +4%
whale oil                 train/study riposte: +10%
wings of a griffon        train/study rampage: +5%
wolf hide                 train/study discipline: +3%