Lora to generate a scene/background of a dirty/messy/dilapidated basement room with an old mattress.

For diversity, I strongly recommend using a Dynamic Prompt wildcard like the one I use:
dirty messy unfinished basement with old mattress {||, {1-3$$barrels|broken glass|{beer|wine|plastic} {bottles|cans}|dirty {clothes|rags}|bucket|mop|old {newspapers|magazines}|{|old {|broken} crt} tv|broken furnitures|{|old} wooden shelves|{|rusty} metal pipes|dangling chains|electrical wires|ceiling rafters}} {||, old torn {posters|stickers} on walls} {||,graffiti}

It is perhaps a bit over-trained, so if the generations tend to be too similar, reduce the strength to the 0.6 to 0.8 range. It depends on the base model you use.