It really depends on what you have. An eighth of nice indoor shrooms has proven too much for me before. Who are you getting them from? Does he consume them himself? When I buy shrooms it's from someone I trust isn't selling me something that'll kill my liver in 2 weeks and who obviously uses his own product. So, when I buy I just ask about the dosage.

Always know what you're buying. Even with photos none of us can accurately judge how potent your shrooms might or might not be.