Here is a simple cobblestone generator. There are 5 tiers available in case people wish to add a multiple versions.

This was made mainly as a standalone block to help servers. It's far more performant to have a single ticking TE then it is a bunch and in-world cobble generation.

But feel free to use as you will. 

Each tier has settings that can be edited in the server config file.

[server.1]

    #The maximum amount of items to hold in the internal buffer.

    #Range: > 1

    max = 64

    #The amount of items to generate every update.

    #Range: > 1

    count = 1

    #The number of ticks between every generation update.

    #Range: > 1 interval = 40

    #Set to true to enable automatically pushing to inventories above this block.

    pushes = true

Thanks Drullkus for making a pretty model for them.

These are the default recipes, but obviously can be edited in data packs.