Success! I'd never been pleased with chrysanthemum petals in rice....but this works!
Chop a few daikon stems finely (with or without leaves, in fact the stems alone make a pretty pale jade contrast to the bright yellow petals), rub in a teaspoon of coarse salt and leave to drain. When limp, squeeze dry and set aside.
Pull petals off half a dozen or so yellow edible chyrsanthemum flowers (most are edible anyway, if not sprayed with insecticide) and toss into a pot of boiling water with a spoonful of mild vinegar. Drain, cool under running water, squeeze gently, and toss with a tablespoon each of mirin (sweet sake) and mild vinegar (preferably rice vinegar, but cider or wine vinegar will do). Set aside.
Into a pot of cooked rice, mix the chopped daikon stems and then the chrysanthemum petals. Don't squeeze again, just drain gently and toss with the rice.
A pretty consolation for tonight's chilly temperatures!