Crayola has a trademark on the smell of its crayons. The odour is described in the Canadian trademarks registry as:

A unique scent of a pungent, aldehydic fragrance combined with the faint scent of a hydrocarbon wax and an earthy clay.

Trademark 1986544

In Canada, a trademark can be anything that is used by by a seller to distinguish their goods or services from those of others, including

a word, a personal name, a design, a letter, a numeral, a colour, a figurative element, a three-dimensional shape, a hologram, a moving image, a mode of packaging goods, a sound, a scent, a taste, a texture and the positioning of a sign.

Trademarks Act

Unfortunately, I have not been able to find records of anyone litigating over a scent trademark.