Fill a medium pot with water and add mushrooms. Make sure the water covers the mushrooms. Boil for 8-10 minutes until the mushrooms just begin to soften. Drain and dry well.
Add the olive oil, red wine vinegar, minced garlic, oregano, rosemary, thyme, Swerve and salt and pepper to taste to a medium mixing bowl and mix well.
Pour the mixture into a Ziploc bag and add the mushrooms.
Marinate the mushrooms overnight and enjoy within 4 days.