Delaware is known as "The First State," so naturally (and quite smugly) the state slogan is "It's Good Being First," as if to say, "We have no further interesting qualities to speak of."
I guess "The Forged Signature State" just doesn't fit on a license plate. One of the signatures on the constitution is that of an absent Delawarean deputy, John Dickinson, added at his request by George Read. (Source)
New Mexico, Land of Enchantment That might be going a bit too far into the whimsy category but there's the slightest chance you'll find some hobbits.
Florida, The Sunshine State Now I want to visit.
New Jersey, The Garden State Now I want a tomato.
Missouri, The Show Me State Euphemisms abound but I'm still intrigued.
Pennsylvania, The Keystone State This says to me "we won't cater our art to you. Google Keystone and then realize how amazing we are at metaphors." I know, I know. "Lou, that sign says 'State of Independance,' you're a liar and I hate you." Look again. That weird green shape, that's a keystone. Boom.
And yes, I like to think that our founding fathers knew Google would exist some day.
Delaware loves being first so much that they pass on or sell original license plates between each other and lower numbered plates are "highly prestigious."
From 1905 to 1909 Delawareans were required to make their own license plates (being first only extended to pen-related matters, obviously). When they began making plates in 1909, they started with 4 digit numbers, making anything lower "the height of fashion."
Being first is so important that The Delaware General Assembly reserved tag numbers 1, 2, and 3 for the Governor, Lieutenant Governor, and the Secretary of State. (Source)
Why the history lesson? The next time you take I-95 South on your trip to watch the Yankees play the Boston Orioles, if you see this type of plate you must stare excessively out your window at them as you pass (like you wouldn't anyway.. You're from NJ), for they are Delaware Royalty and expect as much from the plebes.
I propose a new slogan: "It's good to be first... sometimes." No one wants to be the first person with a new disease (Lou Gehrig) or the first girl in your high school to get pregnant.