Limonene doesn't just smell like citrus, it's in citrus. Lots of limonene. You'll get a ton more limonene from an orange than from a fraction of a gram of bud. All these terpenes are common in food. So I'm skeptical of claims that they have obvious mood-altering effects.

Doesn't mean they couldn't be synergistic, doesn't mean they can't have less obvious effects, but I'd love for somebody to run some experiments with artificial blends.

Right ... OK, old article and no one's reading, but count turpentine too - pure pinene, though I guess it's a mix of α- and β- isomers. There are people who claim they've experimented with mixtures, but no widely published results. Yet, there are unmistakable differences between different cultivated strains, so it's evidently about something more than just % THC.