Hi Kathy, That’s a great question! I haven’t tried it yet, but I think you could try dried mushroom pieces (or powder) similar to infusing something like dried calendula, etc into melt and pour soap base.
Then strain, pour, and it would just be a matter of observing it for some time to make sure the color stays nice and the soap stays fresh.
If you try it first, let us know how it goes, and I’ll put it on my to-do list to test out too! :)