Are you looking for a fern that grows wild in Canada? The first fern that comes to my mind is the Eastern hay-scented fern (Dennstaedtia punctilobula). I wouldn't call the smell eucalyptus-like...it smells sweeter to me...but maybe this is what you're thinking of...

Other possibilities (fern-like or have fern-ish looking foliage but are not actually ferns):

Common Tansy (Tanacetum vulgare): Tansy is native to Europe and Asia but was brought to North America by the British and Europeans. It now has naturalized (i.e. become a weed) throughout much of the U.S. and Canada. It has sort of fern-like foliage, and was believed to repel flies. It is still planted for repelling insects in spite of its noxious weed status in the U.S. The leaves have a strong scent when crushed which some people say smells like camphor mixed with rosemary.

Sweet fern (Comptonia peregrina): This is not actually a fern, but has a fern-like appearance. It is reported to have a scent when the leaves are crushed, but not sure what it smells like. Native to North America.

Salad Burnet (Sanguisorba minor): Native to Europe, and was brought to North America by the British. Some people say it smells like cucumber. Looks sort of like a native maidenhair fern.

Can you post a photo of your fern? To easily identify the name of it.