I am mother of the groom and wondered about my dress colour as the wedding party colours are yellow and grey. I am also wondering what purpose does the wedding cake serve if there is also a dessert, and what size should it be?
As mother of the groom you are one of the few people who will be able to get away with wearing white or ivory, like the bride and her mother, as long as you add in some colour. You could go for a soft ivory dress with colourful accessories such as yellow shoes and a silver grey jacket to coordinate in style
With a colour scheme of yellow and grey I would be careful to wear something that won't clash (unless you really want to make a statement!) You could go for a pale yellow and ivory, a gorgeous antique gold or a complementary shade of peachy orange that will add some different colour without clashing like a bright red or a hot pink would. A blush pink, subdued shade of sage green or a classic navy blue would also look lovely.
With regards to the cake - a wedding cake is traditional and even there will also be a dessert served it is still usual to have a wedding cake big enough to feed each guest. To save money some couples choose to serve their cake as dessert. They could also send a piece of wedding cake to anyone who was unable to attend.