Riddle: I never was, am always to be, No one ever saw me, nor ever will And yet I am the confidence of all To live and breathe on this terrestrial ball. What am I?
Answer: I am tomorrow - your future.
Riddle: There is a green house. Inside the green house, there is a white house Inside the white house there is a red house. Inside the red house, there are lots of babies. What is it?
Answer: It is a watermelon.  Explanation: The skin of the watermelon is green (green house), the watermelon rind is white (white house), the watermelon flesh is red (red house), and the watermelon seeds located in the red flesh are the babies.
Riddle: There is a word in the English language in which the first two letters signify a male, the first three letters signify a female, the first four signify a great man, and the whole word, a great woman. What is the word?
Answer: Heroine.
Riddle: How many three cent stamps are in a dozen?
Answer: A dozen, although you probably said four.
Riddle: When John was six years old he hammered a nail into his favorite tree to mark his height. Ten years later at age sixteen, John returned to see how much higher the nail was. If the tree grew by five centimeters each year, how much higher would the nail be?
Answer: The nail would be at the same height since trees grow at their tops.
Riddle: A beggar's brother died, but the man who died had no brother. How could this be?
Answer: The beggar was a woman.
Riddle: What is bought by the yard and worn by the foot?
Answer: Carpet.
Riddle: What is the value of 1/2 of 2/3 of 3/4 of 4/5 of 5/6 of 6/7 of 7/8 of 8/9 of 9/10 of 1,000?
Answer: One hundred - work backwards and you will understand.
Riddle: What common English verb becomes its own past tense by rearranging its letters?
Answer: Eat and Ate.
Riddle: I dig out tiny caves and store gold and silver in them. I also build bridges of silver and make crowns of gold. They are the smallest you could imagine. Sooner or later everybody needs my help, yet many people are afraid to let me help them. Who am I?
Answer: I am a Dentist.