There may be more species of fungi in my yard than of any other group of organisms , including insects. And yet, so far, I've only found four.
Of course, most fungi are small, live underground, in decaying wood, or as internal parasites of the other yard inhabitants. So they're not easy to photograph and even harder to identify.
But what about the lichens?  There are many lichens in the yard, growing on trees, logs, and rocks. But they, too, are hard to identify, especially from photographs.
But still, I should do better than four!