In small saucepan, combine water and porcini mushrooms. Bring to boil. Remove from heat; let stand for 30 minutes. Drain, reserving liquid. Finely chop mushrooms; set aside.
In small non-stick skillet, saute onion and shiitake mushrooms in 2 teaspoons butter until tender. Add porcini mushrooms and 1/4 cup soaking liquid. Bring to a boil. Reduce heat; simmer uncovered for 3-5 minutes or until liquid is evaporated. Remove from heat. Stir in cream cheese. salt and pepper. Cool to room temperature.
Make sauce: In a samall saucepan, saute button mushrooms and garlic in remaining butter. Add marinara sauce and simmer.
Spoon 2 teaspoons of mixture in center of wonton wrapper. Moisten edges with water, all the way to the filling. Top with another wonton wrapper, pressing down around filling to seal. Crimp with fork or pastry wheel. Repeat with remaining filling and wrappers.
Bring a large pot of water to a boil. Add ravioli. Reduce heat to gentle simmer and cook 1-2 minutes until ravioli float to the top and are tender.