Yes, you can freeze yellow squash without blanching. I first wash the yellow squash using cool water then I cut off both ends. Now cut the yellow squash into slices of about half an inch and put then directly into plastic storage bags. Do not feel the bags. Half full is good enough but remove as much air as you can. Then seal tightly to avoid loss of flavor. I label my bags so that I can remember when I sorted them and use them before six months.