One plant that I suspect arrived in mulch is a native orchid called the Shepherd's Crook or Pink Nodding Orchid - Geodorum densiflorum.
The name Geodorum is derived from the Greek ge - earth and doron -gift
It is a terrestrial orchid which is not evident in winter and has a drooping flower stalk in Jan-Feb. The plants here are past flowering but the photo does show a seed pod. Pollination is by native bees according to the web:
http://www.gloriousnebo.org.au/LOR/orchids/Geod.neocaledonicum.html
That site also has a nice photo of the flowers.
We started off with one plant, but in that area there are now 3 clumps and there is another clump, underneath a very sad looking citrus tree, in a completely separate area.
It seems as if it is common around Brisbane but is a threatened plant in NSW
