eggs (i don't dare try substitutes; if they taste "like" eggs, then...)
tree nuts (almonds, walnuts, macademias, cashews, pistachios, coconut, etc.; everything except peanuts, which technically are legumes..) at least i get to enjoy peanut butter..
99% of fish (except, for whatever reason, pollock.. even then, i tend to only eat the frozen sticks/filets; i don't try eating fish at restaurants at all...); i can't even stand to smell it cooking..
soy (including the milk & other derivatives)
the mild allergies (eggs, soy) make my tongue itch really badly, slightly aggravate my windpipe and give me monster cramps.. after which I have to recline in the restroom for a while..
the extreme allergies (fish, nuts) go even further, contracting my windpipe so severely i can't breathe..
the allergy extends to any recipe that involves any of the above.. which by and large make most pastries and baked goods off-limits for me.. also, many ice cream brands-- especially Haagen-Dahs.. gag..
alas, i've never been able to enjoy birthday cake, twinkies, or ho-ho's without having to throw up..
by default, I usually enjoy a slice of pie for my birthday (making sure that no eggs were used in the crust)..
this tends to make social gatherings with food awkward, as I don't want to appear ungrateful, but I have to tread carefully; often I don't bother asking what the ingredients are in something like a pastry, I just assume it probably involves eggs and I avoid it..