How do you impose an image on another one in photo shop--like if I want an apple to have the look of a pear?

Or .. I want the word Dandelion to show a feild of dandelions, but only within the letters ... in other words, I want one object to take on the coloring of the other but only have the first object remain.
How do you impose an image on another one in photo shop--like if I want an apple to have the look of a pear?
you will have to save your picture of dandelions as a pattern then select it as on a pattern overlay. Open your dandelion picture. then select edit, define pattern. then Once you have your text layer, select layer style, pattern overlay, then select your dandelion pattern

blackheads