Historical clue formulations

• Acorn-bearing tree — 2026-08-10
• Acorn producer — 2026-07-21
• Cask wood — 2026-05-17
• ___ leaf cluster (decoration on a medal) — 2026-03-10
• Sturdy bookcase material — 2026-03-02
• Acorn, in the future — 2026-01-04
• Acorn-producing tree — 2025-11-25
• ___ Park, suburb of Chicago — 2025-06-29
• Acorn-bearing tree — 2024-10-28
• Wood used to age brandy — 2024-07-31
• "Mighty" thing — 2024-04-20
• Cabinet material — 2024-04-10
• Barrel material — 2024-02-17
• Common wine barrel material — 2024-01-31
• Source of hardwood — 2024-01-29
• Hardwood tree — 2023-12-05
• – — 2023-07-23
• Airport across the bay from SFO — 2023-07-02
• Symbol of strength and endurance — 2023-06-20
• Cooper's raw material — 2023-05-21
• Durable wood — 2023-05-07
• Sturdy flooring material — 2023-04-16
• Common street name — 2022-12-17
• Symbol of sturdiness — 2022-11-27
• Popular flooring wood — 2022-07-03
• Wine barrel wood — 2022-07-02
• Kind of branch depicted on German euro coins — 2022-01-13
• Blackjack ___, source of dense wood — 2021-12-09
• Barrel wood — 2021-12-01
• National tree of the U.S. — 2021-10-03
• Good wood for whiskey barrels — 2021-09-14
• Symbol on the Connecticut state quarter — 2021-08-15
• Bourbon barrel material — 2021-04-05
• Acorn producer — 2020-11-25
• Wood rich in tannins — 2020-10-15
• Flavor imparter to chardonnay — 2020-09-23
• Sturdy tree — 2020-06-15
• Symbol of sturdiness — 2020-05-03
• Imparter of flavor to cabernet sauvignon wines — 2020-04-29
• Squirrel's favorite tree, maybe — 2020-02-26
• Tory party symbol — 2020-01-10
• Wine barrel wood — 2019-12-16
• Flooring selection — 2019-11-08
• Symbol of strength — 2019-09-15
• "Talking" tree of a Tennyson poem — 2019-08-07
• ___ Island (storied site of buried treasure) — 2019-07-31
• Sturdy wood — 2019-04-29
• Symbol of strength — 2019-03-14
• Symbol of durability — 2018-11-28
• The ___ Ridge Boys (country/gospel quartet) — 2018-06-06