French Knots add so much texture to an embroidery piece. I love using them to fill in a little (or big) area of space or just to add a little flair to an embroidery piece. French knots are also great for simple things like dotting an i when you are stitching words.
Below is a video tutorial for creating french knots!
One of my favorite patterns that uses french knots is the Wild Daisies pattern. Give it a try :)