The district policy manual is here (see page #7): http://www.coppellisd.com/cms/lib07/TX01000550/Centricity/Domain/1007/CISD_ElementaryHandbook.pdf
I did not see any prohibition of nuts, just prohibition of “no nutritional value” snacks provided by the school during school hours. They do refer you to the Texas Dept. of Ag for national school lunch requirements. But this statement in the policy manual would seem to allow the granola bar in question to be brought to school:
“This policy does not restrict what parents may provide for their own childs lunch or snacks. Parents may continue to bring lunch of any type to their child at school during the school day, but may not share or give any restricted food items to other students.”
Thanks Drago!