I know just how you feel. I have made several rag quilts for friends who have lost family members. It's hard to make the first cuts.
I started when my dad passed and I made grandpa quilts for the four grandsons, using Dad's jeans and flannel shirts. Those were all same size squares. To have enough fabric for the 4 quilts I ended up including pockets and all. Dad did some workworking so many of the squares included splatters of paint and stain. He always had his hands in his pockets so the jean pockets were frayed. It was a teary-eyed moment at Christmas when they got them, but the boys take them with them everywhere.
Since then I've made blankets for friends using sweatshirts, T-shirts and one friend brough her husband's Harley-Davidson boxer shorts. The nice thing about rag quilts is you can use just about anything.