The convoluted/brain-like appearance is caused by numerous disc=like fruitbodies growing very closely together and very often touching Mutual pressure causes some distortion of the disc-like shape. Combine that with the fact that they are touching and you end up with what looks like a convoluted/brain-like mass. Teresa has suggested Bisporella. Certainly plausible if these are growing on wood. However these seem to be growing on soil but amongst bits of wood - but I could be wrong. If on soil, then one of the yellow Phaehelotiums is likely.