Boil 6 eggs until firm; small eggs for 12 minutes and large eggs for 15 minutes.
Cool under running water and peel.
Cut eggs in half lengthwise and remove the yellow yolk.
Using a fork, mash the egg yolks on a dinner plate.
Add mayonnaise to yolks and set aside.
In a cast iron skillet, melt butter.
Mince mushrooms into 1/2 inch pieces and cook in butter until soft.
Scoop mushrooms out and stir into egg yolks.
Mince fresh parsley and also stir into egg yolks.
Salt to taste.
Place bacon strips to the cast iron skillet and fry until dark and crispy on both sides.
Pat bacon dry between two paper towels, then finely chop into little pieces.
Fill egg halves with the yolk, mushroom and parsley mixture.
Top with fresh bacon bits and serve immediately.
Notes
Note: if you aren't planning to serve these deviled eggs until the next day, store in an airtight contain in the fridge. Also, be sure to wait until the next day to cook and add bacon, so it stays fresh and crispy.