The four-leaf clover is a reoccurring element in Rubicon. According to Will Travers it may represent a fourth unknown branch of the U.S. Government when he discovers references to branches of the government and the latin word for four-leaf clover hidden as answers to clues published in crossword puzzles of several major newspapers.
It first appears in the pilot episode, Gone In The Teeth. An ominous sign, the presence of it seems to deliver an as of yet unclear message to its recipient. When Tom Rhumor sees a fresh four-leaf clover inside his newspaper one morning, he looks out of his mansion window and looks at his wife, who waves at him. Moments later he puts a gun to his head and pulls the trigger.
In the episode, Look to the Ant, Katherine visits with Alice Bradley, whose late husband, Gerald Bradley committed suicide under similar circumstances. Alice kept a box of her late husband's belongings with the hope it would help her understand the motives for his unlikely suicide. Alice had also found a four-leaf clover on Gerald's desk and had it encased in acrylic to preserve it. Alice kept the four-leaf clover on display for a while but put it away with the rest of Gerald's belongings as she found it "too morbid" to keep on display.
In the episode, You Never Can Win, Truxton Spangler receives a vase of flowers. He goes to search from whom the flowers originated from only to find a small envelope which contains a four-leaf clover. It is also found on the ledge on the roof of API which Spangler leaves for Will to find.