The Lucky Potato was Ed's first lucky charm shown. It was only seen in "Gimme, Gimme Never Ed" where Ed gave it to Plank for good luck. Unlike Sheldon, Sheldon Jr, and Angus, the Lucky Potato was not treated like a person, but as a thing.
Sheldon was a piece of cheese that Ed kept in his left jacket pocket and he seemed to never throw him away. Sheldon seemed to be like a best friend to Ed, but Eddy and Edd thought Sheldon was disgusting and that Ed should have thrown Sheldon away. Sheldon was about 59 days old when he is first introduced in "Thick as an Ed." Ed never kept Sheldon out of his sight and said he liked Sheldon besides Jawbreakers because Sheldon was more important to him. After a long row of failures to capture the cheese, Eddy managed to capture him and throw him into the Creek, calling for his apparent "death." It was then shown that Ed actually had another "friend" Angus, a fish bone that he wear/wore around his neck. Ed later on got a second Sheldon (Sheldon Jr.) which is seen in "May I have this Ed?," on top of that there are similar pieces of rotten cheese in Ed, Edd n Eddy - Scam of the Century Sheldon returns as Ed's collectibles that Sarah and Jimmy have stolen. It is possible Sheldon is named after Sheldon Arnst, the Animation Supervisor for the show.
Angus is Ed's "more than lucky fishy" that appeared at the end of "Thick as an Ed" after Eddy tossed Sheldon into the creek. He is a skeleton of a fish, possibly of a sardine that has a vile odor, says Edd. Angus, like Sheldon & Sheldon Jr, made only one appearance in the entire series. It is the third lucky charm that Ed owns, the first two were a potato and Sheldon. It is unknown what became of Angus. The appearance of Angus re-igniting the war of Edd vs. Ed becomes the sticky situation at the ending of the episode. He seems to have a Scottish name.
Sheldon Jr. is the second chunk of cheese that Ed keeps in his pocket (after Eddy threw the old Sheldon into the Creek). It was first seen in "May I have this Ed?" It is an exact clone of the original only darker in green, though this may be due to the animation of the show changing. Little is known about this item as it only made a small appearance in "May I have this Ed?" Ed used Sheldon Jr. to impress a dummy, who was dressed as a girl so Edd could practice for the dance, with Ed becoming "Charmin' Marvin."