Welcome to Storyplay - a Different Idea for Every Day
There are many variations, as I’m sure you know, on the mystery bag or box full of objects, to use as stimulus for story creation. You can include a random selection of objects to link together in a narrative, or have one bag of objects/nouns and a box of actions/written verb prompts.
If you still need a bit more of a framework to get going, something like this can help: There was a _ , called _ who was going to a_ in a _ to see a _. On the way _ met a _ and they decided to _ together. The _ was called_. It was _. They were _. Finally they arrived at_ and they both_. _ was _. _ they said, and began to_.
There will probably be disagreements about how the framework should be, but that’s part of it!