Child Behavior: Stealing
There is an enormous chemical reaction that takes place in the brain and body system that literally creates a rush or a release for the child, calming the child. When we can understand that this behavior comes from a place of survival, rather than a conscious malicious act, we can then work to help this child rather than add more stress through consequences and blame.
I suggest talking with the teacher to explain that your daughter is showing signs of being overly stressed in the classroom. Ask the teacher to move your daughter near the teacher's desk so your daughter can feel safer next to an adult. Suggest that s/he check in with your daughter more often, simply by putting a hand on your daughter's shoulder, speaking to her in a soft calming voice or making gentle eye contact with her.
Large group activities, such as recess, can be too stimulating and too stressful for many children, so ask the teacher to provide more teacher/student interaction during these times. Also, you can suggest to your daughter that when she begins to feel stressed and feels like she wants to steal that she can go to the teacher for help. The more ways you can give your daughter to calm herself, the less she will have the need to steal.