Black Doormat in dreams
A mat at the threshold — what you wipe off before bringing the outside into your inside.
How black changes the reading
Black colour pulls the symbol toward the not-yet-known — depth, hiddenness, the part of the situation that has not yet come into the light. The dream is rarely warning you; it is showing you that there is more to the picture than the part you have been looking at.
The base reading of Doormat
A doormat in a dream is the dream's image of the small ritual at the threshold — what you choose to wipe off yourself before you go indoors. The dream brings the mat when the question of what gets to come into your private space with you is alive. A clean doormat used with intent is the dream telling you the boundary at the door is being kept. A doormat worn out, or missing, or stepped over is the dream noting that the small act of separating outside from inside has been abandoned, and the outside has started coming in unchanged.