Fresno County Sheriff's deputies pulled over 58-year-old David Mitchell near Hughes and McKinley Avenues in Fresno.
They initially stopped him because his dog was unsecured on the back of his motorcycle.
Deputies then discovered nearly eight ounces of methamphetamine and $3,000.
During a later probation search of Mitchell's home, they also found a loaded handgun, seven pounds of meth and a pound of Psilocybin mushrooms.
Mitchell was arrested and the dog was taken by Fresno Animal Humane services.