It's lacking depth pixel4hire...
Wuith this in mind I'd suggest 1 of 2 directions.
1. either fade out the 'shrooms UP as they go into the distance (i.e. bring the pallette up on them towards the paler end of the spectrum)
2. or - fade them down towards to darker end of the spectrum
Also. Light source... assuming the light is from above you need to introduce some shading underneath the caps of the shrooms...
...
oh... and remove those stray green pixels that you've got going on the bottom of the biggest 'shrooms cap.
Not sure about the outlines, or at least the lack of AA going into them (in some places) - [but then it's WIP - so you're allowed that]
Finally... where're these ending up? is it part of a background? or are they 'just' stuck on the black...? perhaps you could introduce some grass? (not pot) - the bg determines where to 'push' those shrooms (for depth that is...)
see... rushed eg edits...
ORIGINAL =

DARKER BG = darker pushing of pallette
LIGHTER BG = lighter pushing of pallette
