Open illustrator. Make a new document. I know. We're starting out with the tough stuff first. Well it is only going to get harder from here so buckle up kiddos.
Now go to the retangle tool on your toolbar. Hold down on the little tiny arrow in the bottom right of the tool. The rest of the tools will pop up. Click the star.
Make sure your Fill is black and your stroke is transparent. (if you're new. It's what looks like the foreground/background colors in photoshop.
Hold shift. Make a star. Click the star.
Go to Effect > Distort & Transform > Pucker & Bloat.
Match your settings to mine or be daring and don't. If you go further in the pucker direction it gets sharper. The other direction will give you something similar to flowers.
Go to Object > Expand appearance. This will get rid of the star guidelines. Tada you did it.
(to cluster as a brushpack simply copy your shape. Open photoshop and paste as a smart object. This way you will be able to resize without losing quality.)