These are 4 variations of one simple design, each using free motion stitching a little differently. If you made them rectangular instead, you could make them into cards.
To start, I traced four 5 inch squares on a piece of fabric, about 13 inches square so there is room for some space between the squares. Leaving the four coasters attached for now can be easier than working with smaller pieces, but that works too. Just make sure you add at least an extra 1/2 inch around the edges for something to hold on to, and to accommodate any shrinking or drawing up of the fabric caused by the stitching. I then drew a little heart on each one, stacked that with batting and backing, (I used muslin) and stitched them while they were still attached. Keep scrolling down for individual stitching directions. (A little tip...a heart is much easier to draw if you don't plan on making it symmetrical :-) You can use any simple shape you want, get them from your computer or a coloring book if you don't want to draw one.)
For the first one, I stitched around the outline of the heart first. I then just scribbled all over the rest of the background with my free motion stitching. It is pretty much little messy circles, purposely overlapping. Much easier than trying to make sure your stitches don't overlap! I kind of wish I had skipped tracing the heart. If you do that, you would want to use something removable to draw the line, and make sure your scribbling goes right up to the line so your heart still has definition. Another option is to trace it with thread that matches your background.
Last one! Again, I traced the heart, then made squiggly horizontal and vertical lines going across it. The outline looked messy when I got done with that, since you have to keep traveling on it to get to a new spot. So I did the trick of going around the outline several times again. Then added stippling like the previous one, only with contrasting thread.
To finish your coasters, cut them out at 5 inches, which may now be slightly outside your original lines due to the stitching causing your fabric to draw up. I used straight binding, using the edge of my straight stitch foot as a seam allowance guide. To make narrower binding, just move the needle to the right and you can still use the edge of your foot. The binding should generally be cut 4 times as wide as your seam allowance. Mine was about 3/8 inch seam allowance, so 1 1/2 inch binding strips. There is a nifty binding method with better directions in any of my card patterns, available for download for only $4.75. I am willing to give away lots of secrets, but I can't give them all away, right? :-) You could also add another backing to cover your stitches before doing the binding if you want.