As a Greek, I buy magnets for the fridge, as described heredescribed here.
Notice that I do that regardless of whether my trip was to America, Europe, Africa or Asia (list of destinations). All the magnets I have bought live in Greece.
Notice that this little (easy to carry) can be very special, for example one bought from Monaco was like a wall-frame, made mama smile wide! ;)
Moreover these little cuties can be helpful, since my parents use them to hold notes, cached telephone numbers, etc.!
My father, when in Canada, he brought back home jewelry for my mother. One shaped like the leaf in Canada's flag was very distinctive, and favored by my mother. He also brought Niagara-falls-related stuff, which I don't really remember, except from the classic photo.