In a small saucepan, combine the lemon juice, sugar, water, lemon zest and lavender buds, and bring to a simmer over medium heat. Remove and pour into two standard-size ice trays. Place in freezer until frozen, about 2-3 hours.
When the ice cubes are frozen, you can start your shake up: To the bottom of a 16-ounce mason jar, add ¼ cup of sugar and 2 ounces of water. Stir to dissolve the sugar. Add the juice of half a lemon. Stir and fill the glass with 6 lemon-lavender ice cubes. Top with water. Place the lid on the mason jar and shake, shake, shake until the mixture is ice cold. Remove the lid, top with the lemon half and enjoy!