Record the spread of disease in the garden
There are different species of honey fungus which cannot be distinguished by the mushrooms they produce, but which differ in how deadly they are to plants. It is safe to assume that an aggressive species is present when honey fungus has killed off otherwise healthy plants, and action needs to be taken to prevent spread of the fungus (as described below). Noting the positions of affected plants (past and present) will also be useful in working out which area of soil is likely to contain the fungus and require treatment.
If an already weakened plant succumbs to honey fungus but no others seem affected, infection may have been caused by a less aggressive species. In such cases it may not be worthwhile to go to great lengths to eradicate the fungus from the garden, but instead it may be enough to maintain good plant health to prevent further plant deaths.