Country Singer Jamey Johnson Arrested for Drug Possession and Speeding

Country singer Jamey Johnson's Sunday was far from a funday, as cops hauled him in for drug possession and speeding in Williamson County, Tennessee ... TMZ has confirmed.

The singer-songwriter had a deadly serious stare as cops snapped his mug shot after the Tennessee Highway Patrol made the arrest.

According to News Channel 5 in Nashville, Johnson posted a $5,000 bond before he got out of jail Monday. Cops say the case is still under investigation, and they've yet to release a narrative about what allegedly went down prior to his arrest.

Johnson broke into the country scene with his debut single, "The Dollar," which was featured on his 2006 album of the same name. His success grew with his 2nd album, "That Lonesome Song" ... which saw his single, "In Color" reach the Top 10.

He's since produced several other albums, including "The Guitar Song," "Living for a Song: A Tribute to Hank Cochran," and "Midnight Gasoline."

Johnson has also served as a songwriter for several prominent country stars ... including Willie Nelson, Merle Haggard, Trace Adkins, George Strait, Jessie James Decker, among others.

We've reached out to Johnson's rep for comment ... so far, no word back.