I have thought about veganism, but then i go to the store and see the price and meager choice with vegan replacements and give up. It seems to be easier to just take the cheaper and more abundant base ingredients to cover the bodies base needs.
Luckily unflavored chicken breast and lean cuts of pork(heavily depends on the quality) are amongst the cheapest meats and can be bought in bulk during a sale. Adding in some carb source(potatoes, rice, buckwheat, pasta, quick oats), some greens(paprika, tomatoes, cucumbers, onions, garlic), some dairy products and the basic nutritional needs seem to be covered well enough and cheaply.

As for mushrooms, honestly i can't recall when i ate those last time. I remember from childhood that I really didn't like those, yeah those were kinda odd to eat. But as an adult i seem to have been subconsciously avoiding those.