Pillow stuffers crossword clues commonly point to a few short answers depending on the puzzle and each clue’s wording. Here are the most frequent solutions you’ll encounter, with brief notes on when they appear:

• FOAM (4 letters) — classic filler for pillows and sometimes mentioned in short clue prompts.
• FEATHERS (8 letters) or DOWN (4 letters) — traditional pillow fillings; DOWN is the material from which feathers come, while FEATHERS is a plural fill option in some puzzles.
• EIDER (5 letters) — a type of duck whose down is used for high-end pillow stuffing; appears in several clue sets.
• KAPOK (5 letters) — a plant-based pillow stuffing used in some older or specialty crosswords.

If you share the exact clue wording and letter count from your puzzle, I can narrow down the most likely answer and explain why it fits.