willing to bet you could probably inoculate the soil with local leaf-mold.

Mycorrhizal fungi are different than leaf mold. They have a unique symbiotic relationship with plant roots that no other fungus has. Mycorrhizae live on plant roots, feeding on plant exudates. In return, they act kind of like 'hair extensions' for the roots, absorbing water and nutrients and delivering them to the plant. Mycorrhizae are naturally present in really good soils, but it doesn't hurt to add a bit to the roots at planting time. I've used it for a few years now and it definitely makes a difference, especially when planting shrubs and trees.

I've purchsed it under the Root Boost brand from Gardens Alive, and I 've also found a different brand at my local nursery.

However, the top soil or organic layer from the forest floor can often hold large quantities of various fungal organisms, many of which may form those mycorrhizal associations. Your soil doesn't have to be 'really good' to support these fungi, and there are hundreds of species of naturally occurring fungi that are ready and willing to enter into these highly beneficial root relationships.

Many of our most commonly observed 'mushrooms' are the fruiting bodies of typical mycorrhizal fungi.

I, too, have used mycorrhizal products for many years and strongly recommend them for a wide variety of purposes.

Here is a link that might be useful: PHC Web site