Interestingly, this is what Wikipedia says about celery:

Celery is amongst a small group of foods (headed by peanuts) that appear to provoke the most severe allergic reactions; for people with celery allergy, exposure can cause potentially fatal anaphylactic shock.... In contrast with peanut allergy being most prevalent in the US, celery allergy is most prevalent in Central Europe.

It also says that celery seeds are high in calcium. We learn something (or two somethings!) new every day, I'm sure.