Mona! You can purchase a mold to make patio bricks or pavers !
There are forms for making molds. Also you can make your own out of plywood and some framing lumber to create the box shape.
For more elaborate forms, using foam blocks and carving them to the finished shapes works well also. You simply using 2 inch foam boards, placed inside a wood box that is four inches deep, you use a torch and slightly burn the foam to create an uneven surface. Once you place the cement in the form and it hardens, and you remove the cement, you have the impression that you burnt into the surface of the cement. More often then not you will need to use the torch to burn off some of the foam that has stuck to it, but it works well and you have something other then just a square block of cement.
My neighbor's bought several metal "cobblestone" molds, with the divided sections built in it. Looks nice! God Luck! : )
I was asking a handy friend of mine recently a similar question. We want to make some patio stones with designs in them, for our home, but don't know how to start with the form. He suggested to go to the grocery store, for a cheap alternative, and look at those aluminum cooking pans (one-time use). You can pour your Quick-Crete in there and everything. I don't know if you can use them again for that purpose, but it's a neat idea. ALSO, if you look on craigslist, you can often find silicone or rubber molds from contractors leaving the business or downsizing...worth a look.
oops meant to say... Good Luck : )
You can buy a super inexpensive plastic form at Lowes etc.