photos 4-6 show cystidia with metuloids. Spores 3.9-4.8 x 2.3-3.2µm, Av spore l&w 4.3 x 2.7µm.
Please note photos where taken in dark conditions so the color is actually more grey than the photos shows. Found under dead branch. The pleurocystidia covered with amorphous crystals, spores size and shape, etc. all are a great match for H. singeri. Color shape and it's lack of stipe also make it a great match. Specimen collected for DNA analysis.
Referencing: page 148 of Alberto, E., Fazio, A., & Wright, J. E. (1998). Reevaluation of Hohenbuehelia nigra and Species with Close Affinities. Mycologia, 90(1), 142.
Very small ‘buttons’ growing in oak, maple, beech leaf mast
On clematis: https://www.inaturalist.org/observations/125018611
fungal galls on Clematis virginiana.