Preheat the oven to 375 degrees F.
Toss the squash rings with olive oil and salt and bake on a sheet tray in the preheated oven for 15 to 20 minutes or until the squash is soft and starting to caramelize. Repeat this process with the mushrooms. *Hint - these can be done at the same time! Reserve until ready to use.
Toss together the radicchio, arugula, apple and pumpkin seeds in a medium bowl. Dress with vinegar, olive oil and salt. The salad should be dressed and well seasoned but not soggy.
To serve: Return the squash and mushrooms to the oven for 2 to 3 minutes, just to warm them up. Place a squash ring on a serving plate. Place a handful of the salad inside the ring. Cut the mushrooms into 4 slices and arrange them, fanned, on the side of the salad. Drizzle with pumpkin seed oil.