Due to hygiene concerns, charities tend to avoid used pillows.
Pillows & Bolsters
Blue Bins & Chutes
Pillows are welcome in Cloop bins
Cloop Life Line Bins
Give your old pillow a new life.
Freecycle / Give Away
Some people will take old pillows in order to reuse the stuffing.
Goodness Me! Fabric Destash
Singapore Really Really Free Market
Most charities will NOT accept used pillows.