These are really cute - would be easy to construct, too, with folding of circles for motor skills - not sure if they're just patterned paper circles or cupcake cases, but either would be fine.
You can use any shape. It doesn't have to be a bunny. Just trace a shape or cookie cutter. This would be cute for any holiday, just use an appropriate cookie cutter to trace and cut out the shape, then whatever yarn works best for that holiday!