The obsession became a business in 1985; now his company, Mendocino Mushrooms, exports fungi around the world. Fifty or more part-time pickers bring 27,250kg of boletus, chanterelles, black trumpets, matsutake, porcini and the fabled, maple-syrupy candy caps from forest and field to Schramm's buying stations every autumn; he sells the US$650,000 ($872,000) crop to high-end restaurants and supermarkets in the United States, Europe and Asia. But not New Zealand.
He shakes his head at Kiwis' preference for farmed fungi - "You have great conditions for mushrooms" - cool, damp, dark forests with dense undergrowth.
"Your chefs need to educate people about the unbelievable taste difference between wild and cultivated mushrooms. But people have always been wary of eating wild foods. I think it's a hangover from ancient times - only strange people like Druids ate food from the woods."
Which is why we are in a town you've likely never heard of. It's the opening day of the 12th Mendocino County Wine and Mushroom Festival, sanctified by O, the Oprah magazine, as one of the US' top six food shindigs. We are heading there by train.
It's early morning and at the old wooden Willits train station a smoking diesel locomotive and elderly carriages stand next to the jeans-and-checkered-shirt crowd. It's a scene from a Western. But this was the Wild West - the notorious stagecoach bandit Black Bart plied his trade in these parts.
Since 1885 this railroad has carried massive redwood logs to Mendocino Coast mills and passengers into tiny communities - Pudding Creek, South Fork, Northspur and Shake City.
In 1925 the railroad bosses bought new yellow railcars. The locals called them Skunk trains, now the line's brand name. Why? Gas engines: "You smell 'em before you see 'em."
We chug through tunnels, more than 30 bridges, past meadows and into the forest. We spot a deer drinking from the river. There's a hunter's cabin. A former hippies' commune seems as much a relic as the train.
Then the trainsinger appears with a guitar, in a conductor's suit and cap, braying old favourites: Dinah, won't you blow your horn? The crowd loves it.
At the camp, we cram into the dining hall where chefs stew over the competitive mushroom cook-off. Adam Celaya, Kilkenny Kitchen and Willits Rotary Club tempt with porcini gnocchi, chanterelles soup and three-fungi quiche; 500 of those varieties are edible. We're given a token to drop into the People's Choice wineglass; mine goes to a local mushroom, chilli, cheese dish: it wins.
Back on the Skunk Train, we wind down with the local interpretation of port. The trainsinger changes his tune: now it's a haunting People Get Ready.
We're getting ready for the Winemaker's Dinner at tiny Upper Lake, which was an 1880s stagecoach stop. Back then it might have been a one-horse town. Now Main Street has parking space for 4X4s and is undoubtedly quaint, especially the restored and gentrified 1890s Tallman Hotel and its Blue Wing saloon.
The food, paired with nearby Shannon Ridge wines, is faux-French. Winemakers Clay and Margarita Shannon table-hop, expressing admiration for our sauvignon blancs, but his preference for Aussie over Aotearoa lamb earns the disdain of a table full of Kiwis.
But the month is about mushrooms and the man who once bet his shirt on them.
CHECKLIST
Getting there: Air New Zealand flies direct to San Francisco up to seven times a week. Call 0800 737 000 for further information.
Further information: More information on visiting the northern coast of California is at northcoastca.com.
Ewan McDonald travelled with Air New Zealand and was a guest of Visit Mendocino County.
