a few frozen peas (or just get a few out and leave them for 10 mins or so before giving them to the hams
or you could freeze some slices of cucumber. I used a small food storage box with water and froze it, and gave it to terry when it was hot
he loved it!
also, an icecube in an egcup is nice then they can have a fresh cold drink, you can also freeze babyfood for a frozen food