Nicholas Lander discovers an entirely new product of America's annual harvest

Sunday evening suppers are not supposed to yield gastronomic discoveries and, as I stood on the steep steps of The Gastonian, an extremely comfortable hotel in the historic quarter of Savannah, Georgia, I had no idea that I was only an hour away from tasting a completely new foodstuff.

The short drive to the restaurant, Elizabeth's on 37th, was unusual in itself. The cab driver, I discovered, was a chef during the day; the ten-minute ride took us to the far side of a broad street where the restaurant had been specifically constructed 100 years ago so that it stood, most conveniently, outside the city tax limit, and the magnificent front garden through which one has to walk conceals one of the restaurant's greatest assets – down below are seven airconditioned rooms holding over 16,000 carefully chosen bottles of wine.

The restaurant mirrors the charm of this gentle city. The reception is effectively in the hall from which a series of small diningrooms diverge. From the high windows of the front two rooms are views of luscious sub-tropical greenery and the somehow decadent trees hung with Spanish moss that characterise the city's many squares. And then, as I was about to settle down to a comforting supper, came the realisation that the third appetiser was not quite what it seemed to be.

The description read 'creamy rice with bacon, greens and shavings of pecan truffles'. Now I knew, having spent just 24 hours in this city, that Savannahites are great bakers and lovers of sweet things but I was slightly confused by this apparent juxtaposition of the savoury and the sweet.

And if it was all savoury – as I was assured it was – I was equally perplexed by the price: $12.95 (£8.50) for a starter including truffles, when the last price I had heard for white truffles out of Piedmont was £2500 a kilo, seemed little short of a gift. Which I decided to accept immediately.

What arrived would have graced any table in northern Italy. The rice was as creamy as any risotto only more colourful with the bacon and the collard greens that are so popular hereabouts. Then the waiter appeared with a truffle slicer and my very first pecan truffle which he promptly grated generously on to the warm rice. Seconds later the unmistakable, earthy aromas of truffles filled the air.

A pecan truffle (tuber texense) is as knobbly as its French (tuber melansosporum) or Italian counterpart, only smaller and dark brown rather than black or white. Like the better known European version, this truffle grows in a symbiotic relationship with the tree, in this case pecan tree, and relies on a magical combination of heat and rain – not uncommon in the state of Georgia – to flourish.

The significant climatic changes in France have caused the annual truffle harvest to fall from 300 tons a century ago to an average of six tons recently, a situation exacerbated by urbanisation and industrialisation. But it may well be possible to recreate the right conditions in the right places – a hope on which several truffle entrepreneurs in New Zealand and the United Kingdom have hung their commercial future.

None of these natural disadavantages seems to apply to the Georgian pecan truffle. They grow in abundance under the copious pecan groves in as yet unspoilt countryside; there is a long dry season from January to August followed by heavy rain if not hurricanes; they do not require trained pigs or dogs to smell them out (although squirrels are apparently very fond of them) and they grow so close to the surface of the ground that they could even be harvested by fork. The only sadness for food lovers is that until recently Georgian farmers did not recognise what they were treading on.

At which point I must introduce Tom Brenneman, the hero of this new gastronomic breakthrough. Brenneman is neither chef nor food purveyor but Professor of Plant Pathology at the University of Georgia at Tifton. And like so many other discoveries, pecan truffles came to light by accident.

'I found the truffles while conducting disease control studies in a commercial pecan orchard,' he explained. 'I have gathered wild mushrooms all my life and simply happened upon these in an orchard. I wasn't sure what they were immediately but I collected some and soon determined them to be a true truffle associated with pecan trees.'

Brenneman continued, but only to dampen my obvious enthusiasm. 'Currently pecan truffles are distributed and used on a limited basis and supply is the limiting factor. As with so many native foodstuffs, production is variable and unpredictable and the fact that these grow underground doesn't help. Small quantities are currently harvested by hand from areas where truffles have historically been found and we have attempted some inoculations on seedling trees but the success of these remains to be seen.'

But like so many scientists, Brenneman is optimistic. 'I am sure that there is a commercial future for the pecan truffle. They have had favourable reviews from a range of chefs across the US and whilst they may never replace the European truffle the pecan truffle will one day become a speciality niche market – another unique item from the Old South.'

Professor Brenneman can be contacted on Arachis@tifton.cpes.peachnet.edu