Please offer all old blankets and towels to your local animal shelter. If interested, contact your local outdoor public summer swimming pools, they have many towels every fall never claimed from the lost and found at each swimming pool. Grab them before they go to the dumpster and take them to the animal shelter, so the animals there can have some comfort.
I get the free tarp from HF almost every time I go when they have the free coupons for the tarp. We save them up and take them to the shelter. My wife use to work at a vet and knows all the people at the humane society shelter. They use the tarps for shade in the outdoor kennels in summer and wind breaks on the sides in the winter.
The only problem with this idea is, when I go to the shelter to drop them off one of them dogs always follow me home.