Scott Westell, 36, and 61-year-old Walter Paterson were stopped as they pulled out of a hotel car park in Livingston.
Police were stunned to smell the drugs as they spoke to Paterson about his driving.
A search warrant was then obtained for Westell’s home in Pumpherston, where cannabis worth £500,000 was seized.
He was sentenced to 32 months in jail. Paterson, from Kilsyth, received 27 months.