What I'll often do is to check "yes" for food and then scribble down next to that line what it is that I have. I use this technique for questionable items like lox from Iceland, manchego cheese from Spain, and fruit jellies from France. What always happens is that the customs officer collecting my form looks at what I have written down, asks me to clarify if necessary, and then sends me on my way. I've even gotten the "Why the heck did you check yes? That's not the purpose of the question" look. As a result, if I have food items that I know are acceptable, I won't bother checking yes.

Two related questions:

1. Are you required to itemize on the back if you are below the duty-free allowance? The customs officers never look at it when I do, and I've never been given a hard time when I don't.

2. Does anyone else find it curious that there is no place on the form to explicitly declare alcohol and tobacco, even though such goods have a separate duty-free allowance from the monetary limit? The occasional excess bottle of liquor has entered the USA in my carry-on courtesy of that omission by US Customs.