If the ducks are frozen, thaw them. Rinse the ducks; pat dry with paper towels. Remove the giblets from the body cavities of the ducks and any excess fat. Rinse the giblets; refrigerate until needed. Using a wooden skewer or fork, prick the duck skin all over. (This helps to release the fat during roasting.)
Sprinkle the body cavities of ducks liberally with some of the salt as follows: for sea or regular salt, sprinkle 1 teaspoon into each body cavity and rub another 2 teaspoons on the outside of each duck; rub the remaining onto the skin of the ducks; for kosher salt, sprinkle 1 tablespoon of salt into each body cavity and rub another 2 tablespoons on the outside of each duck. Season with pepper. Set aside.
In a medium saucepan, place farro. Add enough cold water to cover and 1/8 teaspoon salt. Bring to boiling. Lower the heat and simmer, covered, 25 to 30 minutes. Drain; set aside.
Meanwhile, in a medium skillet, cook the bacon over medium heat until soft but not crisp. Remove the bacon, reserving 2 tablespoons of the drippings. Drain the bacon on paper towels; set aside. Add the onions to the reserved drippings and cook. stirring frequently, 4 minutes or until the onions are tender and translucent. Add the garlic, parsley, and thyme. Cook, stirring constantly, for 1 minute. Stir in the drained bacon. Stir the onion mixture into the farro mixture.
Cut the reserved duck hearts in half; season with salt and pepper. Trim the duck livers. Season to taste.
In the same skillet, heat 1 tablespoon of the olive oil over medium heat. Add duck hearts and livers and cook for 3 minutes on each side or until done. Remove from heat. Cool slightly. Chop and stir into the farro mixture.
In the same skillet, heat the remaining 1 tablespoon of olive oil over medium heat. Add the mushrooms and cook until soft. Season to taste. Stir the mushrooms into the farro mixture. (This will not be a very compact stuffing. If you desire a denser stuffing, add the eggs at the end. This will bind the stuffing, making it denser and more compact.)
Spoon the farro stuffing mixture into the duck body cavities. Skewer neck skin to back; tie legs to tail. Twist wing tips under back.
Place ducks, breast side down, on a rack in a large shallow roasting pan. Roast ducks in a 475 degree F oven for 30 minutes, basting every 20 minutes with the fat from the bottom of the pan.
. After 30 minutes, turn the ducks breast side up. Reduce the temperature of the oven to 425 degree F. Roast ducks for 45 to 60 minutes more or until the juices run clear when the thighs are pierced. Makes 8 servings.