I’ve seen pictures of beautifully set tables where people have taken a fresh flower and tied it on top of a napkin by each place setting. Would it be permissible to set a table like that before Shabbos? Would the flowers attached to the napkins become mukzah once Shabbos starts?
Cut flowers are not muktza on Shabbos, therefore attaching them to the napkins will not make the napkins muktza. The flowers should not be placed into water, and one may have to be careful not to make the wrong type of knot when tying the flower to the nakpin on Shabbos, but other than that, it is permitted.