Then last Tuesday, while cleaning his late grandmother’s attic, he found a rusted tin box behind a loose brick. Inside: a leather journal. On the first page, in his grandmother’s handwriting: “Useful material: flint, steel, salt. Knowledge: where to dig, when to plant, how to read the wind. Your grandfather called it the Store of Wisdom. It’s the small shed by the old mill.”

The correct one in some crosswords is: — no.

If you're stuck on more of this puzzle, I can help you find:

After checking crossword databases and common cryptic/set phrases, one answer emerges as the best fit:

The answer to the crossword clue "useful material or knowledge" with the letter count (5, 2, 3, 4) is .

: If the clue says "useful material," and the pattern is long, think of common metaphors or proverbs.

Crossword Answer Websites and Databases - Crossword Solver: Allows input of known letters and length to generate possible answers. University of California, Berkeley ST 3366 (Hints) - Big Dave's Crossword Blog