It depends entirely on the type of foodstuff and how it's packaged. Perishable stuff is obviously not a good idea, neither are tins or bottles. Dried, packet foods work well, as do boxes of wrapped sweets, chocolates, toffees (fill in the customs label with 'candy' though - it helps a lot), fruit cake if well wrapped has passed the portals of Homeland Security unmolested. Try not to send ground coffee or aniseed balls though - sniffer dogs react to these scents as they're commonly used to attempt to disguise drug shipments (I only know this because I work for Her Majesty's Revenue and Customs, not from any personal experience of smug druggling)...

I think I forsee an illegal 'dried mushy pea and Lifesaver' smuggling ring starting up here...

LTS