Vintage metal rice cooker or rice mold, about 5" in diameter. It's clearly been used, but it's in pretty good condition overall, though the aluminum looks a little dull and there's some stains or soil.
We've been told by an older antique dealer that this type of piece was at one time used for making mulled wine, but we've never actually seen one of these in use. And then we saw some more of these on Pinterest, and found it was a rice ball!
We've never seen rice prepared in one of these strainer basket things, but it seems as though they have quite a long history. So use it for rice, or loose teas brewed in bulk, or for mulling spices or pickling spices or whatever else you'd like.