This is a 3D printed Resin base from BiteTheBullet Studio. I’m going to show you the steps I used to paint it.

First, prime the base with a white primer. This allows you to use stains / washes to color it quickly, although you could just start with a brown base coat.

I used a transparent burnt umber acrylic ink from Liquitex to give the entire base an earth tone base, concentrating extra ink on the log and base of the plants (shadowed areas).
I then dry-brushed a grass green over the “turf” and lichen areas, avoiding the log and plants.

I colored the tops of the toadstools with ocean breeze.

Then I used a brighter Holiday Green to paint the ferns.

I dry-brushed apple tart over the lichens on the base.

I free-handed some randomly distributed small spots of bright red on the caps of the toadstools for visual interest.

I also used Coral for the stems of the toadstools.

Finally I used a black wash on the log to darken it and highlight the cracks and bark texture.  (I’m specifically using the black wash from the Vallejo Game Color Washes pack, but any black wash would work.)