Can you please let us know what country/region you (and the compost bucket) are in? It will help with identifying the plant.
Southland, New Zealand. It looks a bit like velvet leaf but i son't think the leaves are as big as my plant. See the peg i have put on it to show the scale.
Hi. I agree that it doesn’t look like velvetleaf, partly due to its very shiny (glabrous) leaves. I went through this key to New Zealand weeds and did not find any good match. Based on the structure and position of its leaves, my suspicion is that it is some sort of bean (family Fabaceae), particularly since it is growing in your compost. This identification can be confirmed if it flowers, as members of this family have very distinctive, bilaterally symmetrical flowers.
The leaves are up to 20 x 30 cm so i'm not sure about that. It almost looks subtropical. It is in my glasshouse. Thanks anyway :-).