@AlisonMilton there are a couple of species this may become, do hope you are able to see it again this morning to photograph and possibly make a herbarium specimen of same. Initially its in the order of Physarales.
@Teresa How do I make a herbarium specimen? This is growing in pot of orchids. Not sure it's good for the orchards but the yellow fungus is growing in the same pot. Leucocoprinus birnbaumii (Plantpot Dapperling)
After examining a specimen I now believe this may be the sclerotia of the Leucocoprinus birnbaumii found growing in the same pot, rather than a myxo - interesting exercise - many thanks Alison - its been a great learning curve