I’ve seen a lot of Climbing Nightshade, also known as Bittersweet Nightshade, wildflowers along the trails on Cape Cod. I took this photograph at Fort Hill down by the marsh although you can see them all along the trails.
Climbing Nightshade wildflowers are a climbing vine with 1/2″ violet flowers swept back from a yellow central “beak” in loose clusters. It forms egg-shaped shiny green berries which turn to bright red in late summer.
Important to note: The berries are poisonous!