1) You can't do anything about being terminated, unless you have an employment contract, the terms of which were violated or breached by your termination. That is because in the absence of a contract, all employment is "employment at will"--you can be fired at any time, for any reason, even unfair or mistaken ones.2) If the believe you stole from them, they could sue you for the balance; to win, they'd have to prove in court that it is "more likely than not" that you took the plants without permission (they can use their managers' testimony; you can obviously deny that based on your testimony, and the court will decide who to believe). It is unlikely that they will go through the trouble of suing for this amount of money, but they have the right to do.3) They could contact the police and try to press charges. Whether anything comes of that will depend on whether the authorities believe that there would be sufficient evidence that, with criminal intent, you took the plants.