I started by chopping and sauteeing the mushrooms.
I poured the egg mixture into a skillet, added the toppings, and let it cook until it started to get pretty firm. It was really a total guess as to when it was firm enough to fold. It started to get bubbles under the surface before I folded it.
Once it got firm, I used a wide spatula and flipped it over (this was not as easy as it sounds) -with a little manuevering, it worked.
Ta-da!! Ham, mushroom, and cheese omelet with a side of fried potatoes. (Fried potatoes courtesy of BD.)
BD wanted his "well done" so I let it cook a while longer. It also dawned on me to flip it again once I folded it over so both sides would brown.