My grandfather recently passed away and I was able to keep a large piece of coal (Yes, a large "lump" of coal) that he personally mined for when he was a kid. I was wondering if it would be an okay idea to display this large piece of coal in my garden as a tribute to him, but I am not sure how this could affect the flowers I already have planted. I currently have Marigolds, Petunias, and roses planted.
I am a beginning gardener so all feedback would be appreciated! Thank you!