Definition from Wiktionary, the free dictionary
mushroomburger (plural mushroomburgers)
- A burger made with mushrooms in addition to, or instead of, meat.
2009 April 12, Larry Doyle, “Iggy in Underland”, in New York Times:
- There’s breakfast at the Rolling Doughnut, lunch at a mushroomburger place, ice cream at Zen Pickle Barrel and pie at Albert Allen’s Rite Spot, and it’s a short book.