By coincidence, I saw a grandmother's flower garden in a book earlier today. The hexagons were trimmed slightly to create curves then bound with a very narrow binding. It had never occurRed to me to do it this way, but it really looked nice.
One of the reasons that I think it worked so well is that all the hexagons along the outside edge were white and the binding was also white. This technique could be used with any color fabric as long as all the outside hexagons are the same color.