In a large saucepan over medium heat, melt the butter. Add the mini marshmallows and stir until completely melted and smooth. Remove from heat and stir in the vanilla extract.

Add the Rice Krispies cereal to the melted marshmallow mixture and stir until well coated.

Allow the mixture to cool slightly, then press it into a greased 9x13-inch baking dish, spreading it evenly. Let it cool completely for about 30 minutes.

Once cooled, cut the Rice Krispies treat into rectangular pieces, about 2x3 inches.

Melt the white chocolate chips and coconut oil together in a microwave-safe bowl, heating in 30-second intervals and stirring until smooth.

Dip one end of each Rice Krispies treat into the melted white chocolate, then place it on a parchment-lined baking sheet. Insert a popsicle stick into the opposite end of the treat.

While the chocolate is still wet, place blueberries on the top left corner of the treat to represent stars. Arrange the sliced strawberries in stripes across the treat to create the flag design.

Allow the chocolate to set completely at room temperature or refrigerate for about 15 minutes to speed up the process.