Mix cheese, corn, onion, garlic, and 1/4 teaspoon each salt and pepper. Gently stuff each blossom with about 1 1/2 teaspoons filling and twist ends of petals closed.
Pour oil into a medium, heavy pot or saucepan until 3 in. deep. Heat over medium-high heat until a deep-fry thermometer registers 360° to 375°.
Put buttermilk and rice flour in separate containers (loaf pans work well, since the high sides prevent spilling).
One at a time, dip each stuffed blossom into buttermilk and let excess drip off. Dip in flour, coating lightly but evenly.
Shake off excess flour and fry blossoms in small batches until golden brown, 45 seconds to 1 minute. Gently submerge blossoms with a slotted spoon to cook tops. Drain on paper towels. Season with salt, sprinkle with chives or basil, and serve with lemon wedges if you like.