No, there is no strychnine in mushrooms. There is no strychnine in LSD, either. In fact, there's no strychnine added to any drugs!
Strychnine was the first alkaloid to be identified in plants of the genus Strychnos, Family Loganiaceae. Strychnos, created by Linnaeus in 1753, is a genus of trees and climbing shrubs of the gentian order. From the standpoint of biological diversity, it is the most important genus of the Loganiaceae family (6 p.1). The genus contains 196 various species and is distributed throughout the warm regions of Asia (58 species), America (64) and Africa (75).
Plants of the genus Strychnos have opposite leaves and bear cymes of white or yellowish flowers that have a four-lobed or five-lobed calyx, a four-parted or five-parted corolla, five stamens, a solitary pistil and bears fruit in the form of a berry. The seeds and bark of many plants in this genus contain the powerful poison (4 p.2). Strychnine is obtained commercially from the seeds of the Saint-Ignatius's-bean and from the Nux-Vomica tree.
Strychnine, the main alkaloid component of the seeds, acts as a bitter substance, which increases the flow of gastric juices. Strychnine is rapidly absorbed into the intestines and exerts its characteristic effects on the central nervous system. Such effects as deepened respiration and decreased stroke volume of the heart through excitation of the vagal center are observed from contact of the alkaloid (1 p.1). The olfactory cortex, auditory cortex, somatosensory and visual cortexes are rendered more acute by stimulation of strychnine, respectively on the frontal, temporal, parietal and occipital lobes of the brain. The action of strychnine also raises epinephrine levels and thus increases systemic blood pressure by direct stimulation of the sympathetic nervous system on the smooth muscle of the arterioles. This action can be of great value in reducing cardiac failure. The most direct symptoms caused by strychnine are violent convulsions due to the simultaneous stimulation of the motor or sensory ganglia of the spinal cord; this can be of value during chronic lead poisoning and during surgical shock. Strychnine can also be used as an antidote in chloroform (a volatile heavy toxic liquid used as a solvent or veterinary anesthetic) poisoning.