I agree with the others as to it being a 4 patch posey which is also known as a 4 patch kaleidoscope.
https://www.connectingthreads.com/tu...lock__D20.html
The purple corners are snowballs. Basically, a small square of purple that you sew diagonally on each of the corners and then trim off the excess underneath.
https://www.thesprucecrafts.com/snow...tterns-2821221