I find a great way to learn how to draw just about anything is to look at it. I love to draw flowers, and have found a great site to use as a drawing reference: Flowers.VG. On this site you can find just about every flower at every angle possible. Overall, the site have more than 11,000 flowers, as well as little garden creatures.
It is important to remember when using a reference in your art is not to copy it. Most pictures are copyrighted. If you copy these pictures you will be breaking the law. It's kind of like downloading a song or movie you didn't pay for.
If you would like to learn more about drawing flowers, see our article: Drawing and Painting Flowers and How to Draw Leaves.