I don't have hayfever, only very mild symptoms if anything (horsehair is the bad one for me). I have problems with some fruit although, wierdly, not always.
Apples, strawberry and kiwi fruit tend to do it, I get little sore lumps and a tingly feeling on the inside of my mouth. I figured it was maybe some kind of pesticide or something that irritated it or maybe more delicate bits getting iirritated, hence it only happening sometimes. They tend to calm down within a couple of hours.