Preheat even to 375 F.
Halve, seed and slice the acorn squash into 1/2 inch crescents.
Toss w/ 1T olive oil + S&P and place in single layer on baking sheet.
Roast for ~30 minutes, or until tender. Add mushrooms to baking sheet last 15min of cooking time.
Season salmon with S&P and in the same oven, roast for 18-22 minutes or cooked through and flaky.