Which items can be crafted and uncrafted back

Solution 1:

To my knowledge, these are the "compact storage" blocks in which you re-obtain its base material, in Minecraft as of 1.16;

Haybale (9 wheat)

Dried kelp blocks (9 dried kelp)

Slime blocks (9 slime balls)

Bone blocks (9 bone meal)

Coal blocks (9 coal)

Iron blocks (9 iron ingots)

Gold blocks (9 gold ingots)

Redstone blocks (9 redstone dust)

Lapis lazuli blocks (9 lapis lazuli)

Diamond blocks (9 diamonds)

Emerald blocks (9 emeralds)

Netherite blocks (9 netherite ingots)

The following compact storage blocks have to be mined rather than crafted to get its base materials back;

Melon (9 melon slices)

Snow (4 snow balls)

Clay (4 clay balls)

Glowstone (4 glowstone dust)

Edit as of 5-25-21:

Honey blocks (can be crafted with 4 honey bottles, but to get its base material back you must put a honey block and 4 empty bottles around it in the crafting menu to get 4 honey bottles back)