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California Flat-Top Agaricus

California Flat-Top Agaricus (Agaricus deardorffensis), photo
Photo: reagan peschke, CC BY 4.0 · iNaturalist
Agaricus deardorffensis · Family Agaricaceae · Updated October 2026
56US records
3states
Novbusiest month
56 US records since 2005 (41 in the last 10 years)

Last seen Dec 19, 2025 (about 10 months ago) in Sanborn County Park, CA, photographed by an iNaturalist user, with the ID agreed on by other iNaturalist users (research grade). Most US records come from California, Washington and Oregon, and the busiest months are Nov, Oct and Dec. (Data as of October 26, 2026; records can lag by weeks.)

⚠ Never eat a wild mushroom based on this site. We show where fungi have been recorded, nothing more. We never say any mushroom is edible or safe, and you shouldn't decide that from any website, app or photo. Many deadly mushrooms look like harmless ones. If someone may have eaten a wild mushroom, call Poison Control at 1-800-222-1222 right away.
Lookalike warning. Many mushrooms, including deadly ones, closely resemble each other, and the only reliable identification comes from an expert looking at the actual specimen (often with spore prints or microscopy). Never use a name, photo or record count on this page to decide what something is.

When it's recorded

Jan3Feb1Mar1Apr1May0Jun4Jul0Aug0Sep0Oct17Nov20Dec9

Records by month, all years. Busiest: Nov, Oct, Dec.

Where it's recorded

StateRecordsLatest sighting
California37Dec 19, 2025
Washington17Nov 3, 2025
Oregon2Nov 2, 2022

Top counties

More on this species from GBIF.

Bring along

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Regional mushroom field guideSee on Amazon
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Folding mushroom knife with brushSee on Amazon
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Wicker foraging basketSee on Amazon
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10x hand lens / loupeSee on Amazon
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Spore print paperSee on Amazon

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