Place oats in bowl of a food processor, making sure to cover the bottom. Add raisins, almond butter, honey, and vanilla. Process for 1 minute or until mixture is finely chopped and forms a paste when pressed between your fingers. Press about 1 tablespoon of mixture around each grape, rolling to make a smooth ball. Roll each in almonds, if desired, lightly pressing into the surface. Cover and refrigerate until ready to serve. May be prepared 2 days ahead.