I went to the local Tuesday Morning, which looks like a huge junk shop and is a terrible mess. However, I have found some good stuff there and my pal KitKat swears by it. I knew I needed a large urn-shaped vase, and found a great pottery one for $19.99. It's cream and has a raised pattern on it, which echoes the marble fireplace surround. I then went to the florist and found some huge heads of hydrangea in greeny-bluey-browny colours. Since their stems were long, I thought they might work and I can just let them dry out for the next month or so. I need to add something else to fill out the vase, and am looking for that.
Thanks for the suggestion, Ally!