Whatever the mood strikes me to put in.
My base is always a little bit of low fat mayo. Just enough to help it stick together. From there, I add whatever I'm in the mood for. It could be any of the following (but generally not all at once!
):
Relish (sweet or pickle)
Celery
Boiled egg
Apple (my g'mom used to add chopped green apple and it always takes me back)
Nuts
Red and green bell pepper
Dijon mustard
Curry powder
Paprika
Frozen peas (I know, sounds weird, is really yummy)
Water chestnuts
Shredded carrot
Baby spinach leaves (chopped fine and mixed in - great way to get in an extra serving of veggies)
.