Preheat the oven to 450°. Rub the chicken all over with 2 tablespoons of the olive oil. Season the chicken inside and out with salt and pepper and set it in a roasting pan, breast side up. Rub all but 1 tablespoon of the herbs over the chicken, covering it well. Scatter the garlic cloves in the pan and roast for 15 minutes.
Reduce the oven temperature to 350°. Slowly pour 1/2 cup of the white wine over the top of the chicken, being careful not to disturb the herb crust and roast for 15 minutes longer. Reduce the oven temperature to 300° and roast for 30 minutes. Pour the remaining 1/2 cup of white wine over the chicken and roast for about 40 minutes longer, until an instant-read thermometer inserted in the bird's inner thigh registers 165°.
Meanwhile, in a heatproof bowl, soak the dried morel mushrooms in the boiling water until softened, about 10 minutes. Drain the morels and rinse well; reserve the soaking liquid.
In a large skillet, melt the butter in the remaining 1 tablespoon of olive oil. Add the drained morels and season with salt and pepper. Cover and cook over moderate heat until glazed, about 3 minutes. Carefully pour in the reserved soaking liquid, stopping before you reach the grit at the bottom. Boil until the liquid is reduced to 2 tablespoons and stir in the 1 tablespoon of remaining herbs. Cover the morels and set aside.
Tilt the chicken to drain the cavity juices into the roasting pan and transfer the chicken to a large carving board. Peel the roasted garlic cloves and transfer to a small plate. Pour the juices from the roasting pan into a small saucepan and skim off the fat. Transfer 1/4 cup of the juices to a large bowl. Stir in the sherry vinegar and season with salt and pepper. Add the watercress and toss well. Add the remaining juices and the roasted garlic to the sautéed morels, reheat and season with salt and pepper.
Carve the chicken and serve with the watercress salad and morels.