is your mil from minnesota, perhaps? i went to college in northern iowa, and know a lot of minnesotans. a minnesotan "salad" is usually jello (often lime) with fruit and dairy product (usually whipped cream, but i've had cottage cheese too). i don't know the etymology of them calling it a "salad" other than the fact it is served as a side dish to a meal instead of as a dessert.

of course, i've always liked them, so you can take my opinion with a grain of salt.