Lilacs are definitely edible. Just be sure that the lilacs you are using are pesticide free. You can use lilacs in simple culinary ways like infusing sugar, alcohol and simple syrups. You can bake with lilacs and mix cocktails or sip some lilac lemonade. Garnish a lemon cake with lilacs, bake them into scones, or even add them in some whipped cream. The culinary uses for lilacs are limitless.