Preheat oven to 375 degrees.
In a large bowl, stir together the rice, vegetables, pepper, salt, thyme, soup, water, milk and mushrooms.
Pour into a lightly greased 9x13 baking dish. Cover with foil and bake for 30 minutes.
Remove from oven, uncover, and top with dough rounds.
Return to oven and bake for another 20-25 minutes, or until pastry is golden brown and filling is bubbly.
Let stand 10 minutes before serving.