Michael Shannon in Jeff Nichols' "Take Shelter."

Celebrity seekers -- keep an eye out for Michael Shannon, Sam Shepard, Sarah Paulson, Ray McKinnon, Joe Don Baker and Paul Sparks, who have all joined the cast of director (and Little Rock native) Jeff Nichols' film Mud, starring Matthew McConaughey, Reese Witherspoon and Tye Sheridan, according to Deadline New York. 

Production on Mud, which is being filmed in Arkansas, began Monday. Celeb sightings surrounding the film are pouring in. Witherspoon's already been seen shopping in Dumas and Little Rock. And earlier this afternoon, the actress had lunch at Cafe Bossa Nova in Hillcrest, according to another tipster.

Shannon is getting Oscar buzz for his starring role in Nichols' soon-to-be-released Take Shelter. He's also a major player in HBO's Boardwalk Empire, which had its season premiere Sunday.

Mud concerns two 14-year-old boys who run into a fugitive (McConaughey) who needs help in escaping capture and assistance in rekindling an old romance (the former girlfriend is played by Witherspoon).

Website thefilmstage.com says that Shannon will play Galen, an uncle to one of the boys, and McKinnon and Paulson will play one of the boys' parents. Shepard will play a recluse named Tom Blankenship.