Bandit Treasure Quest:
Fast travel to Old Haven and follow the left wall. You will eventually reach a pile of dead bandits where one of them is breathing his last few breaths. When he opens his hand he will be holding a glowing strongbox key that will start the quest. Make sure you have a corrosive weapon or two and some health packs because you're going to need them as you search Old Haven for the other two keys.
Green Thumb Quest
To get the Green Thumb quest, fast travel to the Middle of Nowhere Bounty Board. Get a car from Scooter's and drive to the right. Notice the small shack with big plants around it. Talk to the man leaning against the shack to start the quest. Then travel across the bridge to the east side of Rust Commons East. Follow your map marker to the valve. Avoid the small bandit camp set up near the valve. Drive to Jaynistown and attach the valve to the marked pipe in order to turn off the water.
Added by: Sanzano Dec 18th 2009, ID#5275