My 11 mo DS2 is developing a talent for exploring the underside of his plate, normally followed by dropping it on the floor or putting it on his head.
With DS1 we had a rubber mat thing that had suction cups fitting it to the table on one side and to the plate / bowl on the other. For the life of me I can't find them around now and the bowls with suction cups we've tried just don't stay put (we've got an oilcloth tablecloth on our table which may not be helping).
Have you found anything that works for you?