Preheat oven to 350 degrees with two racks evenly spaced. Butter two 9-by-2-inch round cake pans; line with parchment paper; butter again. Dust bottoms and sides with flour, and tap out excess. Set aside. Into a medium bowl, sift together flour, baking powder, and salt three times. Set aside.
In the bowl of an electric mixer fitted with the paddle attachment, cream butter on low speed to soften. Increase speed to medium, and beat until fluffy and light in color. Keep beating while gradually adding sugar; beat until fluffy, about 3 minutes. Beat in vanilla.
Gradually drizzle in beaten eggs, beating between additions until the batter is no longer slick, scraping down the sides twice. With the mixer on low, alternate adding reserved flour mixture with milk; starting and ending with the flour. Mix until just incorporated after each addition. Scrape sides of the bowl; mix 10 seconds longer.
Divide batter evenly between the pans. Bake in lower third of oven until a cake tester inserted into the center of each comes out clean, about 40 to 45 minutes. Transfer the pans to a wire rack to cool for 10 minutes. Remove the cakes from the pans, remove parchment, and return to the rack to cool, top-sides up.
To assemble, turn cakes upside down. Using a long serrated knife, slice each cake in half horizontally. Place a layer on a cake round or cake stand. Spread top of layer with 1 1/2 cups frosting. Stack the second layer over the frosted layer; spread another 1 1/2 cups of frosting over top of this layer; repeat with third layer; cover with top layer. Using a dry pastry brush, gently brush any loose crumbs away from cake. Frost cake thinly to seal in crumbs. Use 3 cups frosting for final coating.
To decorate, evenly distribute cream-colored sprinkles over the top surface of the cake.
Using an 1 1/8-inch gum-paste petal cutter, cut petals out of jellied citrus slices -- you will need 84 petals. Gently press 14 small gumdrops around the perimeter of the cake, spaced evenly apart; arrange 6 jellied petals around each drop to form flowers. Transfer to a large cake stand -- ours measures 19 inches across.
To make the maypole, you will need a wooden dowel, painted white, and six pieces of 1/8-inch satin ribbon, each three times the length of the dowel. Gather the ribbons together, and pin them through their centers to one end of the dowel. Gently press a Lifesaver over the pinned ribbons, and top with a small gumdrop. Insert the maypole into the center of the cake, and fan the ribbons out around the cake stand, taping in place and letting the ends trail over the table.