The myth

If birds eat uncooked rice, the grains will swell inside them until their
bellies burst and they die.

The "truth"

There are, apparently, weddings all over the USA (and, increasingly,
elsewhere) where kind-hearted guests throw bird seed at the
newlyweds instead of the traditional raw rice. Their precautions are
as unnecessary as they are touching; not only will rice do no harm
to any bird, it forms part of the natural diet of some species.

Somehow, the rice myth has become entangled with the modern
trend to ban confetti from venues; though this is done to limit litter,
many people believe it's because confetti is another potential
chough-choker. However, says the RSPB, don't give birds very salty
food, such as salted peanuts or crisps-that might well kill them. (It
will also make your wedding look a little coarse.)