Cannabinoids are known to occur in several plant species besides Cannabis.
See Rudolf Bauer et al., CB Receptor Ligands from Plants, 8 Curr. Topics in Med. Chem. 173, 173-86 (2008), detailing plant species in which cannabinoids are known to occur besides Cannabis, including coneflower (Echinacea), oxeye (Heliopsis helianthoides), electric daisy (Acmella oleracea), Helichrysum umbraculigerum, liverwort (Radula marginata), black pepper (Piper nigrum), chocolate (Theobrama cacao) plants, as well as Echinacea purpurea, Echinacea angustifolia, Acmella oleracea, Helichrysum umbraculigerum, and Radula marginata, with lipophilic alkamides (alkylamides) from Echinacea species being the best-known.
R. Bauer, P. Remiger, TLC and HPLC Analysis of Alkamides in Echinacea Drugs, 55 Planta Medica 367, 367–71 (1989) identifies at least 25 different alkylamides, some of which shown affinity to the CB2-receptor, like a cannabinoid. Same with Stefan Raduner et al., Alkylamides from Echinacea Are a New Class of Cannabinomimetics: Cannabinoid Type 2 Receptor-Dependent and -Independent Immunomodulatory Effects, 281 J. of Bio. Chem. 14,192, 14,192-206 (2006).
Nigel B. Perry et al., Alkamide Levels in Echinacea purpurea: A Rapid Analytical Method Revealing Differences among Roots, Rhizomes, Stems, Leaves and Flowers, 63 Planta Medica 58, 58–62 (1997) noted that while cannabinoids are found throughout the plant, they are most concentrated in the roots and flowers in some Echinacea species. As did Xian-guo He et al., Analysis of alkamides in roots and achenes of Echinacea purpurea by liquid chromatography–electrospray mass spectrometry, 815 J. of Chromatography A 205, 205–11 (1998).
Allesia Ligresti et al., Kavalactones and the endocannabinoid system: The plant-derived yangonin is a novel CB1 receptor ligand, 66 Pharmacological Research 163, 163–169 (2012).
G. Korte et al., Tea catechins’ affinity for human cannabinoid receptors, 17 Phytomedicine 19, 19–22 (2010).
Sciences 9099, 9099–9104 (identifying a common dietary terpene–beta- caryophyllene, a component from the essential oil of cannabis and other medicinal plants–as a selective agonist of peripheral CB2-receptors in living organisms).
Giovanni Pacioni et al., Truffles contain endocannabinoid metabolic enzymes and anandamide, 110 Phytochemistry 104, 104-10 (2015).