When I implemented sand & gravel support in Underground Biomes, those used some textures that were removed later due to complains about them looking weird, not vanilla-like enough, etc. But some peoples still liked them, so, here's your option to use them again!
Now with 1.14.x+'s new textures, another upcoming pack will come with stones adapted to those new textures.
You may contact me trough Github or my discord.