Gluten-Free Blackberry Muffins

I have a large patch of vining blackberries and marionberries that grow up my fence and onto the support wires above. Each year they produce an abundance of beautiful berries that I need to freeze or use as they ripen on the vines. Grazing on these antioxidant-rich berries all day during the hot summer feels wonderful too. Some days I'll only eat the raspberries, blackberries, marionberries, and cherries growing on my property until dinnertime! These muffins are a great way to use some of the blackberry harvest, but you can use any type of berry in this recipe in place of the blackberries if needed!