This is a very interesting stitch that leaves scope for some experimentation. A series of straight stitches are used to overlap each other to develop a symmetric shape like square, circle, heart, etc… This stitch can be worked nicely over even weaved fabric, but this tutorial will illustrate it over normal fabric. Rhodes stitch can make great filling textures. 

I will demonstrate a square shape using this stitch. So, I will work inside a square drawn on the fabric. The outline of the square will be the stitch line for the rhodes stitch.

rhodes_stitch_1          rhodes_stitch_2
Fig 1: Start by coming out from one corner of the square shape, the point A. Take the needle in at the opposite end, point B.    Fig 2: Now, come out from C, a point near point A. Go in through D, a point opposite to C. Then, again come out through E, and continue with this process. 
rhodes_stitch_3   Fig 3:  A finished square looks like this. Since the straight stitches run from one end to the other, overlapping each other at the center, it gives a ‘spinning’ appearance. 
This technique can be used to make any shape, especially symmetric ones. So, try circle, triangle, and heart shapes too.