candles

I don't think the river stones go well there. You can go to a fireplace/outdoor kitchen showroom and then sell colored glass. Maybe go with a hot red or clear glass and then put things in it such as candles or white antlers or hurricanes that tie in with the surrounding brick this way you have a touch of modern a pop of color and the more traditional brick surround. Also you could print off a large stencil and stencil the white brick in back in a repeating pattern stencil.