Health-promoting effects of medicinal mushrooms have been postulated for centuries in folk medicine in Asia and Europe and are currently being verified by scientific research. Lion's mane (<i>Hericium erinaceus</i>, HE) is an arboreal medicinal mushroom that has been shown to improve short-term memory of healthy mice, and to modulate stress-coping strategies of rodents. HE shares bioactive compounds with other arboreal medicinal mushrooms such as the pink oyster mushroom (<i>Pleurotus djamor</i>, PDJ) and agarikon (<i>Fomitopsis officinalis</i>, FO), but their effects <i>in vivo</i> have not been investigated. The aim of this study was to compare the effects of dietary supplementation with HE, FO, or PDJ on long-term memory, anxiety-like behavior, and hippocampal gene expression of healthy male mice. CD-1 mice were fed with either control or mushroom-supplemented (2 mg/g of dry chow) diets for 40 days and underwent object novelty recognition and elevated plus maze tests before hippocampi collection. Only HE-supplemented animals displayed long-term memory (one sample <i>t</i>-test against chance level of novelty preference ratio). Supplementation had no effect on anxiety-like behavior, but its effect on the frequency of arm visits of the elevated plus maze apparatus was modulated by the amount of ingested food - an effect that was absent in control animals. We also observed that mice with higher weight gain had lower expression of <i>Gsk3β</i> and <i>Mtor</i> in their hippocampi. We discuss the relevance of these results for rodent behavioral studies of dietary mushroom supplementation.