Cabbage, Chinese Chomping -
Calming Draught -
caterpillars -
cleaning solutions, magical -
cockroaches -
Confusing Concoction -
Confusing & Befuddlement Draught -
cough potion -
crocodile parts
Hermione studied a diagram of this when the fifth years were researching potion ingredients in the library for Snape (OP16)
Calms emotional turmoil.
Madam Pomfrey gave this to Hannah Abbott after she burst out crying in Herbology and said she was too stupid to take exams and should leave the school (OP27)
Sliced caterpillars are used in Shrinking Solution (PA7).
Cleaning and polishing is usually accomplished with magical means, including various potions.
Diluted Bundimun secretion is an ingredient of certain magical cleaning fluids (FB)
When Ron had to polish awards in the trophy room, he came back into the dormitory smelling of metal polish because he had not been allowed to use magic for it (CS8)
In preparation for the visit by the delegations from Durmstrang and Beauxbatons, the castle was spiffed up. Armour was polished and oiled so it didn't squeak when it moved. Some of the more dingy paintings were scrubbed so that their subjects sat with their faces pink from the effects (GF15)
In Britain these are also referred to as "black beetles". Black beetle eyes are sold at the apothecary's in Diagon Alley. The rate was five Knuts a scoop the summer before Harry's first year (PS5).
Snape keeps a jar of these (dead ones) in his office (OP28)
Effect is to cause confusion.
Confusing & Befuddlement Draught
Effect similar to that of Confusing Concoction.
ingredients: sneezewort, scurvy-grass, and lovage
Medical magic: unknown, but presumably treats a cough.
Weasleys' Wizard Wheezes' Owl Order Service repackages some of their potions as cough potions to get them past security checks, such as Filch's blanket ban on their products at Hogwarts (HBP15)
Ron once threw a crocodile heart at Draco Malfoy in Potions, so they are used as potion ingredients (PA10).