On both sides of the salmon fillets (just one side if the salmon has skin on one side), sprinkle salt and pepper.
Heat a large non-stick skillet on medium heat and add half of the butter (1 tablespoon), reserving the rest of the butter to add shortly.
To the skillet add sliced mushrooms and garlic. Stir together.
Continue cooking the mushrooms while stirring until the mushrooms start to brown (about 5 minutes). Watch the garlic closely, if it starts to brown too quickly, turn the heat down to low.
Turn the heat to the skillet off for just a moment and move the pan to an unused burner on the stove. To the pan, add the Marsala wine and remaining butter. Stir together.
Then return the pan to the burner and turn the heat back on to medium heat and stir.
To the skillet, place the salmon fillets (skin side up if the salmon has skin on it).
Cover the skillet with a lid.
Let cook until the salmon flakes when tested with a fork (about 5 to 10 minutes depending on the thickness of the fillet or preferred doneness).
To Serve - To serving plates, add warm cooked brown rice and sprinkle toasted shelled sunflower seeds on top (optional).
Transfer the cooked salmon fillets from the pan on top of the brown rice and top with the mushrooms.
Drizzle the remaining juices from the skillet on top of the salmon and serve.