Each episode title is a place mentioned in the book where Sam-I-Am offered Guy to try the titular dish. True to the book, Guy refuses to do so, saying he will not eat them in said location (ie Train, Car, House, in the Dark, etc).
At the time this was the most expensive animated series roughly costing $6M per episode. Multiply that by 13 and the result reveals $78M. It has since been surpassed by other series.
In an interview with Ellen DeGeneres, Michael Douglas said he signed onto the Green Eggs and Ham series because even though his acting career after The Streets of San Francisco (1972) was mostly films, he was at a late point in his life where he wanted to try new things and only did voice acting a few rare times before Green Eggs and Ham.
Michael Douglas, usually known for playing dangerous or seedy types, plays against type, voicing Guy Am-I, a grouchy and finicky but good-hearted everyman and law-abiding citizen whose only previous felony was jaywalking.
Tree is the only key location from the book that is not a title in the first season.