Unfortunately the combination of 'white' and 'roughly spherical' provides almost no information. These might or may not be truffles. In a case like this I'd, ideally, cut one vertically in half and show the inside in a photo. Of course, the ideal is not possible if you don't happen to be carrying knife, scissors, etc. Then I'd carefully run a fingernail across the middle of the fungus at the top to create a small break in the skin. Then I'd look for a tough eucalypt leaf to see if I could use that to cut through the fungus, in a back-and-forth saw-like motion. If that doesn't work the last resort is to gently pull the fungus apart into two halves.