My parents had several rose bushes growing along the front of our house while I was growing up.  There were several different colors, and some bushes fared better than others, but the yellow rose bush was always the most productive and had the prettiest flowers on it.  When my wife and I were dating years ago, I would frequently clip a yellow rose off the bush and take to her for no special occasion just to say "I love you."  It became a very special sort of trademark thing for us, and to this day whenever there is a special occasion, or even still just for no special occasion, I still send her yellow roses.  She says she prefers yellow roses to red any day because of the sentimental connection to our dating years.  (Interestingly, we are moving to Texas soon, where the yellow rose will take on additional meaning.)