1. Put lavender buds in a small bowl. Pour 1/4 cup boiling water over the buds and let steep 10 minutes. Strain the scented water into a bowl and set aside; discard buds.
2. In a 4-quart pan over medium-high heat, combine peaches, raspberries, sugar, and lemon juice. Bring to a boil and cook, stirring often, until liquid has the consistency of thick maple syrup, about 14 minutes. Stir in the lavender water and boil, stirring often, another 2 minutes, or until mixture reaches desired thickness (see notes).
3. Remove jam from heat and let cool for 15 minutes. Chill, covered, at least 2 hours before using. Jam keeps, chilled, up to 4 weeks.
Note: nutritional analysis is per tablespoon.