This feature was exclusively part of a joke version and is not currently planned for addition to regular Minecraft. It is documented here on the wiki due to being officially-released content by Mojang Studios, even if not present in a final version.
The texture of a very fine item resembles the side face of a grass block with the words "Home Sweet Home" written on it. Unlike most items, its texture is 64x64 pixels, rather than the usual 16x16.
A very fine item was obtained only from an item frame in the isolation dimension. Only existing in 2020 April fools snapshot 20w14∞, it cannot exist in any non-April Fool's joke versions and April Fool's joke versions before or after 20w14∞.