I was unaware these were called 'buckeyes' until some midwestern friends informed me of their correct name. They were sort of an ad-lib dessert for a vegan/gluten-free catering job. I kept the recipe when I saw how fast they disappeared.
Cream peanut butter and powdered sugar in bowl of an electric mixer. Add rice cereal and mix until incorporated. (I find that using a whisk attachment, as opposed to the paddle attachment, crushes up the cereal a bit more effectively and results in a better texture.).
Using a meatballer or a spoon, scoop out bits of the mixture and roll into 3/4" balls. Cover either two dinner plates or a cookie sheet in parchment and space the balls about 1" apart. Place in freezer for 15 minute to harden.
Melt chocolate in a double-boiler over the stove or on 50% power in your microwave for about 2 minutes, stopping to stir once. Remove peanut butter balls from freezer. Poke one with a toothpick and swirl about 3/4 of the way up the sides in the chocolate mixture. Return it to the parchment and repeat the process for the remaining candies.
Return tray of completed buckeyes to the freezer for 20 minutes, or until chocolate has hardened. Keep in freezer or refrigerator until serving. If frozen, allow to thaw 5 minutes before serving.