My list
GOOD: Payday bars, crunchy granola bars, fig newtons, salted mixed nuts, hard boiled eggs (cool weather only).
For relaxed rides, we, DH & I, are also fond of bike picnics with fancy bread, canned oysters, good cheese, fruit, all that. Just don't overpack/eat. There is also something to be said for stopping at small diners/bars/greasy spoons for a burger - or whatever.
BAD: Bananas (how do people gag them down?), chocolate (just not tasty when I'm working), anything fragile, anything expensive.
Give big space to the festive dog that make sport in the roadway. Avoid entanglement with your wheel spoke.
(Sign in Japan)
1978 Raleigh Gran Prix
2003 EZ Sport AX