Answer:
I can be simple or I can be complex. I can be found in this riddle or in everyday life. I can be shapes or even colors.
Railroad Crossing, look out for the cars. Can you spell that, without any R's?
I go from house to house a messenger small and tight. Whether it rains or snows I sleep outside at night.
A thousand wheels, but move I do not. Call me what I am, call me a lot. What am I?
I have thirteen hearts but no body or soul.
What can never be put in a saucepan?
What am I?
Animal
Difficult
Easy
Food
Funny
Kids
Logic