That means they contained pot.
Police say they were contacted after several fifth graders at Stoneman Elementary School shared nibbles of the Flintstones' sugary cereal treat.
The student who brought the treats to school knew they contained pot, police say. The student had obtained the treats from her adult sister.
A couple of students told school staff, who contacted police and paramedics, said Pittsburg school superintendent Barbara Wilson.
The older sister told police she received the pot treats from a medical marijuana dispensary. Pittsburg police are investigating whether the sister had a legitimate card to obtain the pot.
Lieut. Brian Addington of the Pittsburg Police Department said the students who tried the treat had ingested minute amounts of pot.
Story Contributed by CBS Affiliate KPIX.