Pretty much everything that you can take legally as a supplement won't exactly cause euphoric effects. The ones I've mentioned make me happy by relieving anxiety, so treating the symptoms that make me unhappy. There is also mucuna pruriens, which is 99% l-dopa. It increases the availability of dopamine in the brain, the "reward" neurotransmitter. Also 5-HTP, which readily converts to seratonin. These can be bought online and in health food stores. Purple lotus flower has no real supplementary value, and is supposedly mildly euphoric when smoked. It's perfectly legal as it has no potential for abuse. That might be as close to what your looking for as I can get.