I belong to this Facebook group called the Iron Writer, anyone can join it by the way,and it is a wonderful and supportive writing group.
We do these weekly flash fiction challenges where four elements are given and anyone in the challenge has to use all four elements, anyway they choose in a 525 word max. story.
For instance, four elements can be something like:
a cactus plant
An element can also be a video or a picture. The only limit is your imagination.
Then you have to write a story using each of the elements in it.
The stories get voted on and a winner is declared and will participate in a future tournament.
Making up elements and using them in a flash fiction story is a great way to develop imagination, help with writer's block, will help with grammar and are just fun to do.