While not a prevalent flavor in the United States, rose is fairly common elsewhere. Across the Middle East, particularly Iran, it is used to flavor all manner of sweets. Ice cream is the only use of rose in food that I have found palatable. Rose candy tastes like grandma’s perfume to me, and rose scones just taste wrong. But the ice cream gives a nice rounded sweetness that is just right for such a delicate flavor. The rose petals themselves are not really potent enough to stand up to the amount of sugar and cream that ice cream requires, so it’s fleshed out with rose water.
Rose water can be found at most Middle Eastern grocery stores and at specialty stores. The potency of the rose water will vary from brand to brand, so you may want to start of by whisking in one teaspoon at a time until you are satisfied with the flavor. I used Nielson-Massey, which is pretty strong.
Rose petals should be unsprayed, or organic. The best would be from a friend or neighbor, as they would be the freshest. Otherwise try natural foods stores or a florist/nursery specializing in organic flowers.