Above three: Dead Moll’s Fingers (Xylaria longipes), on sycamore
Oyster Mushroom (Pleurotus ostreatus), on Ash.
Ophiocordyceps ditmarii, above and the three images below.
I found these two different species (above and below) of micro-fungi under oak leaf litter, whilst trying to find another Cordyceps. They were both only approximately 0.2 mm long.