It's "didn't eat" in the sense that it was in the food I paid for, but I took it out. In case you can't tell, it's mushrooms.
I don't regard myself as a fussy eater, but unfortunately there are great swathes of common foods that I don't like. Coconuts, marzipan, cinnamon and dill pickles are some of the individual things I don't like, but mushrooms is a whole class of foodstuff. Along with mushrooms, I don't like fish, seafood, poultry, alcohol or anything too hot (as in spicy).
Other than that, I'm generally fine. It does mean I'm useless at entire cuisines, though: Portuguese (all poultry), Indian (too spicy), French (laced with alcohol) and Essex University canteen food (mushrooms in everything) are problematical examples. Yes, of course there are some foods from these cuisines that are just fine, but if I do go to a restaurant specialising in them I'm looking at a very restricted menu.
I've no idea why my sense of taste takes against these things. My maternal grandmother didn't like poultry either, but she liked Christmas pudding (which I don't).
At the university today I had a choice of fish, curry, some vegetarian tart with mushrooms in and the "pasta bolognaise" I eventually went for that I discovered also had mushrooms in so I had to pick them out.
Next time, I think I'll just try get a burger from the fast food joint there instead...