Peeping through

This lovely pot of white hyacinths arrived in the post today but has presented me with a dilemma. It's from my ex MIL, three Christmases after her son and I separated. Until now we have exchanged cards for birthday and Christmas but never gifts , so to say I was a little surprised is an understatement. Now how to respond ( apart from phoning immediately to say thank you which of course I have already done) ?