Subject to the fact it's the wrong time of year, it would be more
likely to be Choiromyces meandriformis, which is found on the surface
- but of (broad-leaf and/or frondose woodland.

Thanks for that - A little research makes me 99% sure it's Choiromyces
gangliformis:

http://www.rogersmushrooms.com/galle...Block~bid~6940
~source~gallerychooserresult.asp

Shortened: http://is.gd/rmbI

It centainly looks like a member of the Choiromyces family, and the
'knobbliness' of it makes gangliformis very likely.

You haven't said where it was found. Truffles are usually associated
with specific trees, and in any case, in the summer/autumn

It was found in a wooden plant trough in a suburban garden. Not quite the
right habitat, but the pictures and description are compelling.

Cheers,

Al.