Einstein wanted to be cremated and his ashes spread in a secret location to avoid creating a shrine or anything weird.

He got the weird instead. Dr. Thomas Harvey, the pathologist on call the evening Einsten died of a burst aortic aneurysm, stole his brain.  Why? Who knows why, he was no brain specialist.  He got  retroactive permission from Einstein's son, Hans Albert, as long as the brain was used for scientific purposes, whatever that was supposed to mean. Einstein’s eye doctor, Henry Adams, got the eyeballs from Harvey and they are sitting in a safe deposit box in New York, presumably also for 'scientific purposes'.
Harvey had a technician cut the brain into more than 200 pieces. Many were saved properly, but others ended up in jars in his basement. Then when he moved to the Midwest, they sat in a cider box stashed under a beer cooler. Then, when he wanted to meet Einstein’s granddaughter, he put the jars in the back of a reporter’s Buick Skylark.
That part of the story would at least make Einstein laugh.

On Thursday, two of the pieces that Harvey saved properly will go on display to the public in London’s Wellcome Collection museum.  So what if it's only two pieces?  It's still part of Einstein's brain. As a sign in his Princeton office proclaimed: “Not everything that counts can be counted, and not everything that can be counted counts.”

Einstein’s Brain Arrives in London After Odd Journey - ABC News Radio