Bunker style Buffer Stops, prototype made from sleepers on end, backfilled with soil/cinders/old ballast. Often seen overgrown, so can scenic to choice.
These model ones are lasercut from MDF, woodgrain scribed, with facing board cut from quality art-board. Designed to slot fit onto track, and front recessed to avoid damage to couplings.
Paint / stain as desired aand back-fill with whatever you have on hand.
Complementary Acrylic Set-Square included to make assembly easier.