I've done those before and depending on how detailed you want them to be, you can even try them without a pattern or cutter. They are pretty simple. I just cut out the shape with a knife and rolled them, putting a stamen (or whatever that yellow thing is called) in the center. I had bought a silk one from the craft store to use as a reference - and it ended up pretty close. I used gumpaste - just because you can do more delicate work with that. Okay, that probably wasn't too helpful. Someone else???
i have read that you can use a heart cookie cutter for the bloom. you can cut that out and gently flatten the edges and curl them out. roll it up , touch up the shape and then make a stamen with paste rolled around a wire, and rolled in petal dust or chalk, insert the stamen, add the greenery, hang upside down to dry, then paint with dry petal dust or luster dust. i've got to give these a try for a wedding cake in a few months, just havent had the energy to do it yet.
I made tons of these for a wedding cake--it helps if you make the stamen (it's not actually a stamen but I can't remember what it's called) first-- roll a sausage shape a little shorter than you want the finished flower--make it fatter at one end and hook a wire (22-24 gauge) and insert into the fat end. Let them dry for a couple of days, then brush with diluted egg white (or meringue powder) and roll in colored sugar or cornmeal (for pollen). Let dry. Then cut out your heart shape or use a cutter (I ended up buying a set of cutters from Global Sugar Arts) and cut out your petal--roll the edges to thin and ruffle slightly. Brush the stamen with egg white, and wrap the petal around it. Shape the flower gently and dry upright (I used a styrofoam shape set I bought at Sugarcraft) for 10 minutes or until it starts to hold its shape. Then you can hang upside down to dry. HTH 
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