I ran out of car candy last week and so my son and I went to Bulk Barn. While there replenishing my supply of assorted candy we found Shamrock Sprinkles. OMG we had to get these.
My son and I baked cupcakes (from a mix - did not have time to make a from scratch cake) for his class, I iced them quickly and he put on the Shamrock Sprinkles!
Hope this inspires your own creativity...