The large horse-mushroom, except for catsup, should be very cautiously eaten.
"The Mirror of Literature, Amusement, and Instruction, Vol. 12, Issue 332, September 20, 1828" by Various
Stall-fed horses might be fed a ripe mushroom every day or two.
"Studies of American Fungi. Mushrooms, Edible, Poisonous, etc." by George Francis Atkinson
The horse mushroom has pink gills and may be found from June to September.
"The Mushroom, Edible and Otherwise" by M. E. Hard
In support of his stone-horse, he should have produced a chesnut-horse in the vegetable sense; a daisy-horse, or a mushroom-horse.
"Notes and Queries, Vol. IV, Number 99, September 20, 1851" by Various
But horses weren't the only ones benefitting from the medicinal mushroom-based products — knowing the supplements were safe for humans, too, trainers and jockeys started taking them.