Any prompt will deliver different results when used again and again, but there are some that are particularly useful and versatile. You can use them to generate new ideas or to freewrite on an existing topic. Here are a few to keep handy: I remember… / I see… / I think of… / I feel… / I want to write about….
All of these can also be changed to their opposite: I don’t remember… / I don’t see… / I don’t think of… / I don’t feel… / I don’t want to write about…. These versions can access quite a different part of the psyche, digging into what is in shadow. It can be interesting to alternate between both versions in one freewrite.