Hymenotorrendiella eucalypti

The fruitbody is consists of a shallow cup atop a stem. The cup may be up to about 2 milimetres in diameter and the stem up to a millimetre or so long. the The upper surface of the cup is more or less flat and whitish, creamy or yellow. Otherwise the fruitbody may be darker (e.g. greyish ochre, brownish). There are scattered, straight, tapering, brown hairs around the rim of the cap and they are up to half a millimetre long. The hairs show easily with a 10X handlens but can break fairly easily. Sometimes you see stumps rather than full-length hairs.  

The fruitbodies develop on fallen Acacia phyllodes.

The first published description of this species, based on material collected in Tasmania, appeared in 1860 and in that publication it was named Peziza eucalypti, under the mistaken assumption that the fruitbodies were on eucalypt leaves. Spooner (see references) re-examined the original collection and found the substrate to be Acacia phyllodes, not eucalypt leaves. He thought this species also grew on leaves of a variety of plants but Johnston et al (see references) found that what Spooner though to be just  one species with a wide host range was in fact a group of species, with different host preferences, and (on page 19) say that Hymenotorrendiella eucalypti is "Acacia-specialized and very common on the recently fallen phyllodes of Acacia in native forests of Australia. It has been found also on Acacia in Spain, New Zealand and Chile where it is exotic, having been imported along with its host. This fungus is likely to be an endophyte in the living phyllodes of Acacia".

Look-alikes

The features mentioned in the first paragraph and the Acacia phyllode substrate should make this species easy to recognize.  There are other species with long, brown hairs - but with fruitbodies not on Acacia phyllodes, or without stems. There are species with stemmed cup-like fruitbodies but with short hairs densely packed around the margin.

References

Johnston, P.R., Park, D., Baral, H.-O., Galán, R., Platas, G. & Tena, R. (2014). The phylogenetic relationships of Torrendiella and Hymenotorrendiella gen. nov. within the Leotiomycetes, Phytotaxa, 177 (1), 001–025.

Spooner, B.M. (1987). Helotiales of Australasia: Geoglossaceae, Orbiliaceae, Sclerotiniaceae, Hyaloscyphaceae, J. Cramer, Berlin/Stuttgart  (=Bibliotheca Mycologica, 116).