Crying Obsidian was intended to be a block that can change your spawn point, but it was never added to the game. This mod implements this block and adds an item version of it.
Crying Obsidian
This block allows you to set your spawn point to your current location. Just place the block and right-click on it. If you successfully set your spawn point, a message will be shown in the chat.
Crafting Recipe
Crying Obsidian (Item)
Works exactly like the Crying Obsdidian block, but it is an item so you don't have to place it to set your spawn point.
Crafting Recipe
Advanced Crying Obsidian
Works like the normal Crying Obsidian block, but it can only be used by its owner (this can be disabled in the config) and an entity can be bound to it. To bind an entity to the advanced Crying Obsidian block, right click on the entity with the Crying Obsidian item. After that, left click with the Crying Obsidian item on the advanced Crying Obsidian block. The entity that is bound to this block will respawn at the position of the block if it dies. If the "re-spawn whitelist" config option is enabled, only entites on the whitelist can be bound to an advanced Crying Obsidian block.
Crafting Recipe
Crying Obsidian (Decoration)
This block is only for decoration and can't be used to set your spawn point, but it is cheaper to craft.
Crafting Recipe
Additionally, there is a config option that disables sleeping in beds.