Pesach Questions

Are there other foods that fit in same category as milk & eggs (i.e. can only be bought without a KLP hechsher before the holiday starts)? What about other foods that don't require a pesach hechsher such as black tea, coffee, salt, or sugar? Can these all be bought on the holiday without a pesach hechsher?

The custom pertains exclusively to milk and eggs, due to their proximity to grains that might be ubiquitous on farms. All other foods that can be purchased without special Pesach certification may equally be purchased before and during Pesach.

RYK