So I picked up an old magazine at a flea market recently, and was shocked by some of the bizarre foods that people used to eat. The July, 1964 issue of Family Circle Magazine contains a treasure trove of Ripley's Believe-it-or-not type creations that I hope no one was really eating.
It seems at the same time kids were running out and buying the new Beatles 45's, their moms were making lots of gelatin based foods. How about Chicken Indienne? That's a molded gelatin filled with chicken breast, curry, celery tops and chutney.
Or, as pictured below, the Ribboned Vegetable Relish mold, made with beets, carrots, finely chopped spinach, Italian dressing and lemon-flavor gelatin.
Now my dad used to make a delicious jello creation that include lime Jello, shredded cucumber, and pineapple...which even his grandkids loved. But I don't think you're ever going to get kids to eat Jello filled with beets or spinach.
Here's one that might not be too disgusting. It's called Ship-a-Heroes, made with cold cut sails and bread filled with egg salad. At least if you didn't want to eat it you could launch it in the bathtub and see if it floats.