From Canada I've never met anybody who hated poutine, although it's almost impossible to find vegetarian unless you make it yourself. Maple syrup is also much beloved although whether that's a food or an ingredient might be open to interpretation

For something more divisive I look at the lobster roll, or probably just lobster in particular. The traditional recipe comes from a time when lobsters were still poverty food, and it's literally just lobster, mayo, and lettuce served on a hotdog bun. It became popular in fancy-ish restaurants and tourist traps and costs far more than it should. The simplicity of the recipe does little to hide that a lobster is a sea bug, although the flip side is that simple food is often really quite good and homey.

Honorary mention goes to dulse, a type of seaweed. This one's a fairly popular tourist export along the coast, and while I do like a nori or roasted seaweed, I think this shit is nasty. Although I suppose the tradition is to eat it raw so I've never tried cooking with it, it certainly left an impression that scared me off of it