what do you mean "herbal cigarettes"? I guess a lot of people think you will mean dope! but im thinking maybe you mean those ones without any tar / nicotine etc, I think they may have an indian on the packet?
ahhhhhhh I dunno. they are pretty rank. chances are he prob thought he was being cool, will "smoke" 2 of them then chuck them away or give them to a mate.
I'd be tempted to laugh at him. this may shame him into realising he's being a bit of a doosh in true 15 year old style.
And yes he " could" be using them to smoke weed, but chances are he's just being a teen and experimenting. (I would keep an eye out for evidence of weed smoking tho just in case) Again, these are nasty and seem like a cool idea to a young teen, but I doubt the novelty will last as long as a packet.
I guess it's up to you if you feel this is a big deal. If you do, say something to him, if you don't, just leave it.
Don't laugh, ask to try one in a friendly way. Make no big deal about any of it - just get him to smoke them outside.
And ignore the hair/piercings - just make sure he realises he might need to comply with a school uniform policy so may need to take them out in 2 weeks - dd had hers done in the summer so they were healed before school started and could be taken out.
I hate the piercings and the ridiculous hair but it's not my body - and 2 years after having a grotesque belly button thingy done she's now taken it out of her own accord.
Save your ire for things that matter like being able to get into college/completing GCSEs and getting a job.