This quest you actually get BEFORE you join the brotherhood... or at the very least before the jester Cicero visits. You see, Cicero's wagon is STRANDED with a broken wheel on a road NORTH of Whiterun, near a farm called "Loreius Farm". Go talk to Cicero on the road and he'll beg you to help him convince the farmer up north to help fix his wagon, starting this quest.
Head north into the farm and find the owner, Vantus Loreius. Ask him about Cicero and Vantus will tell you that its not a matter about payment but that he just feels... feels that Cicero is a nutjob (and oh man, does this guy have INSTINCT or what!?). He really doesn't want to help. However, you'll come to a dialog choice where you can either convince him to help, or sway to his way of thinking:
o HELP VANTUS
Ask Vantus what you can do to help. Vantus will tell you that a guard patrols nearby fairly often and wants you to report Cicero to the guard. Head back down to the road and find the guard, then use any of the three persuade options to get him on Cicero's case (I picked war contraband and was able to get away with it at 29 Speech Skill). Afterwards, go back and talk to Vantus to recieve a reward of 400 Gold Coins.
o HELP CICERO
Despite his reluctance to help Cicero, tell Vantus that Cicero is a stranger that needs assistance. You'll then have to pass a persuade check to convince Vantus that he should help Cicero (I was able to do this at 29 Speech Skill). He'll agree. Return to Cicero and let him know and he'll be overjoyed, giving you a reward of 400 Gold Coins.