Stop spending "way toooooo much money" with your local florist or calling 1-800-flowers or 1800flowers.com. I am going to share how to make your own birthday flower cake. You can use silk or fresh cut flowers.
Use a knife to cut floral foam into the shape of a cake. For ease of cutting choose a square style, or try a round style for a different look. If you want to mak a cake with two tiers, cut one shape approximately three inches larger than the other on all sides. Then place the smaller shape on top of the larger ones and poke thin dowels or wooden skewers through both layers to hold them together in two to four places. If using fresh flowers, wet your floral foam and then place it on a plate or a shallow bowl; if using silk flowers skip the wetting process.
Cut your flower stems with scissors. Each stem should be approximately two to three inches long.
Start at the base of the largest foam shape. Poke the stems of your flowers into the foam, lining them up side by side all along the lower side edge of the foam. When that layer is complete, continue to layer more rows of flowers on top until you have covered all of the surface of the craft foam.
Stick a candle in the top of the flower "cake" for decoration. Be careful about lighting it, though, as you might damage the flowers if you do.