In a blender, combine fresh blackberries and honey (or agave syrup). Blend until smooth.
Strain the blackberry mixture through a fine mesh sieve to remove the seeds, if desired. Set aside.
In a separate bowl, whisk together the Greek yogurt, fresh lemon juice, vanilla extract, and a pinch of salt until well combined.
In popsicle molds, alternate layers of the blackberry puree and the lemon yogurt mixture, starting and ending with the yogurt layer.
Use a skewer or a toothpick to gently swirl the mixtures together for a marbled effect.
Insert sticks into the molds and freeze for at least 4-6 hours, or until fully frozen.
To release the popsicles, run warm water over the outside of the molds for a few seconds.
Notes
Serve the popsicles on a rustic wooden board or a colorful plate. Garnish with a few fresh blackberries and lemon slices for an enhanced visual appeal.