My spinach has bolted...
 

....and it's no big whoop, but I have a question:

Is there anything I can do with the stalks of the spinach plants? I
went away for four days, and it went from low-lying rosettes to tall,
spiky bolted spinach. The stalks look like they'll have a watery,
celery-like consistency, but I was just wondering if there's something
toxic in spinach stems that I need to stay away from.

Thanks

Mark