I never throw out any scrap of yarn, the tiniest pieces are collected in baggies.
Some are used for stuffing, some go out for the birds to build their nests in the spring.
Any yarn long enough for granny squares goes into an old picnic basket. I keep a dedicated I-9 hook in the basket and when the mood strikes me I crochet granny squares. When I have enough accumulated I use a full skein of yarn to join and turn them into granny square projects, afghans, shawls, etc, but mostly afghans. I get about 6 "unexpected" afghans a year that way.
Any yarn ends too small for granny squares but longer than 10 inches get tied together and wound into a ball of "found yarn"
I use this found yarn to crochet Chi Ba Ba for my local Vet's office who work with the animal shelter.
Chi Ba Ba's are merely C2C blankets made in the size of pet cages or crate to aid the animals they treat.
Attachment 12951