From the site Therapist Aid, is a summary of the 5-4-3-2-1 Technique for re-grounding in the moment. Focus on identifying:
5 things you can see. “Look for small details such as a pattern on the ceiling, the way light reflects off a surface, or an object you never noticed.”
4 things you can feel. “Notice the sensation of clothing on your body, the sun on your skin, or the feeling of the chair you are sitting in. Pick up an object and examine its weight, texture, and other physical qualities.”
3 things you can hear. “Pay special attention to the sounds your mind has tuned out, such as a ticking clock, distant traffic, or trees blowing in the wind.”
2 things you can smell. “Try to notice smells in the air around you, like an air freshener or freshly mowed grass. You may also look around for something that has a scent, such as a flower or an unlit candle.”
1 thing you can taste. The summary suggests you could chew gum or eat a snack and “focus your attention closely on the flavors,” but for this one I might substitute thinking back to a recently enjoyed taste, or looking for something in your environment that reminds you of a taste, etc.