This one requires some explanation. In 2004, Michael Stadther published a children's book called A Treasure's Trove, which contained clues for twelve jeweled creatures collectively worth $1,000,000 hidden across America.
The method for solving the puzzles involved making a 5x5 grid as shown above, filled with the alphabet minus the letter Q. Groups of coordinates were then hidden in illustrations. For example, shown on either side of the grid above are flowers with different numbers of petals. The flowers to the left of the grid (one petal on the left, one petal on the right) indicates the coordinates (1,1) or the letter A on the grid. The flowers to the right of the grid (three petals on the left, four petals on the right) indicates coordinates (3,4) or the letter N on the grid.