What other foods can I be allergic to if allergic to mushrooms? What cross reacts?

Several. People with mushroom allergy are sometimes prone to something called "oral allergy syndrome" in which they experience oral itching and or rashes around the mouth. This can occur even with exposure to outdoor mold spores. However, several foods have been implicated - interestingly, the common link seems to be those foods that also have molecular similarity to latex.