The Maiden caught me in the wild
Where I was dancing merrily
She put me into her Cabinet
And lock'd me up with a golden key
This cabinet is form'd of gold
And pearl and crystal shining bright
And within it opens into a world
And a little lovely moony night
Another England there I saw
There is no literal cabinet, he’s just locked in her embrace. He’s completely consumed with her. And there is no gold, pearl, or crystal, it’s just showing what he sees the relationship as at first. In the beginning, he sees it as completely perfect and wonderful, like gold, pearl, and crystal.
The Crystal Cabinet