I made my own pattern for a stocking for first grandchild and added appliqued snowmen. I used a Debbie Mum Christmas book as inspiration for one snowman and free-hand drew the other and a tree. I used white buttons from my mother's button box for falling snow. The back side of the stocking is a quilt block in matching colors (Carolina Lily, as my granddaughter's name is Lily). I'm going to make another this year for my new grandson.
You can try using children's coloring books for applique ideas and create your own patterns. Enlarge or reduce on a copier to get the size you want. There are generally a lot of holiday-themed ones available at dollar stores and WalMart, and you can likely find coloring sheets free online. Holiday cookie cutters can also offer simple shapes. I have a reindeer cookie cutter that would work well as a pattern, as well as an angel, bell, stars, holly leaf, candy cane, etc.