In a small bowl, mix the pesto, sun-dried tomatoes and herbed cream cheese. Fill mushroom caps with a large spoonful of the cheese mixture. Top with small slices of provolone cheese and a green onion garnish. Place mushrooms on a baking sheet.
When ready to serve, bake for 15 to 20 minutes, or until mushrooms are slightly tender and the cheese is nice and melted. Serve warm!