Minecraft wiki entry for Metadata_variants, associated text: 1 Removed in 1.8 (14w26a)
1.1 Faceless pumpkins and jack o'lanterns
1.2 Faceless and exceptional furnaces
1.3 Weird pistons
1.4 Six-sided hay bale
1.5 Green shrub
1.6 Overgrown cocoa
1.7 Overgrown wheat
1.8 Overgrown melon and pumpkin stems
1.9 Overeaten cakes
1.10 Minor removed block variants
1.10.1 Invisible stairs
1.10.2 Wall sign with full block hitbox
1.10.3 Invisible random ladders
1.10.4 Incorrectly modeled torches
1.10.5 Strange buttons
1.10.6 Bottomless and bricking hoppers
1.10.7 Nether portal post
1.10.8 Boring variants
1.10.8.1 Blocks that did not use block metadata at all
1.10.8.2 Blocks that used only some of the available block metadata
1.10.8.3 Weird variants eventually replaced with normal blocks
2 Removed in 1.13 (17w47a)
2.1 Redundant seamless double slabs
2.2 Snowy dirt and snowy coarse dirt