What does popcorn, tully monsters, and fluorite have in common?

What do the following 15 items have in common?
* Eastern Tiger Salamander
* Northern Cardinal
* Monarch Butterfly
* Square dance
* Bluegill
* Violet flower
* Popcorn
* Gold Rush Apple
* Tully Monster
* Big Bluestem
* White-tailed deer
* Fluorite
* Painted Turtle
* Drummer silty clay loam
* White oak

These are all OFFICIAL symbols of Illinois. What fun and odd conglomeration of things. I'm sure there's meaning behind each of these choices, but it's funny that together they should really say Illlinois, but I'm not sure I'd look at this list and say, "Wow! That's Illinois"

It would be fun to have a game where there are 50 lists like this, and you have to try to match them up with each state. I'd play that game on Facebook.