I make a craft foam ( I love that stuff ) berry. A strip of red foam about 5/8" wide and rolled up on a hook to make a cylinder. Use CV glue on one side of the foam strip. After the glue dries cut the cylinder into the shape of a mulberry and then take some strong thread to wrap the 'berry' in 2 axis' to create the ridges of the berry and tie off. Adjust the color with sharpies. Floats forever and is quite durable except when a carp breaks you off.
It is a very realistic looking mulberry. You can also glue a short green stem into the end of the roll for a stem. I will try to find the sbs and post it.