A speaker with idle time on their hands starts wondering whether anything is left untouched. The poem's wish is for a world that hasn't been used up: a patch of silence not drowned out by car horns, a scrap of earth not fenced off or paved over.
The grammar gives the game away. Ordinary words get bent into verbs and passives: "keep off the grassed," "my wifed." The signs and rules that claim land have turned into something done to the land, and the last line carries that over to a woman. She is something that has been "wifed," claimed and labelled like the lawn. The final line, set apart on its own, lands with a small jolt, and its meaning is open. It could be a rueful, slightly dark joke, or it could suggest the speaker sees marriage as one more kind of ownership.
The mood is restless and wistful, with a dry humour underneath. Boredom turns into a quiet longing for something wild and unclaimed.