THE YAMADAN by Lynne Gessner
Two boys camping with their father must contend with The Yamadan, a native American legend with the power to transform anyone who sees it into a monster just like it.
The Yamadan, and the boy in its grip, who is slowly tranforming into one himself.
MONSTER BLOOD by Charles Land
A 12-year old boy who is obsessed with monsters volunteers to be assistant to a scientist whose speciality is an extinct monster called a Basilisk. The Basilisk, as described here, is a large beast that is part chicken, part snake, with an evil-eye that kills any living thing that looks upon it, including itself.
This boy is wearing specially crafted glasses that protect him from the Basilisk's deadly gaze.
The professor brings a Basilisk to life using a potion made partially from the boy's blood, hence the title "Monster Blood".
Tigger's the one on the left, a super-evolved descendent of the modern housecat. The story is told first-person, from his perspective.
Tigger and his human partner Ellie encounter a fearsome alien while searching for plantlife.
THE SPELL OF SPIRIT STONES by Alice Wellman
In this surreal story, Nancy, a woman living at an American research camp in Guyana, accompanies an Akawai Indian shaman into the forest to visit her tribe. She encounters several monsters, including the large bird pictured, which carries her off and drops her into a forest of tree-like ghouls.
Later Nancy is attacked by a huge anaconda. Her shaman friend transforms into a jaguar to do battle.
THE NIGHT CREATURE by Richard R. Smith
In the second science-fiction story in this collection, a scientist lets his 12-year old nephew in on a secret device he's developed that enables levitation. They both take it for a test ride in the night sky, only to be attacked by a mysterious octopus-like flying "night creature."
Luckily the scientist also developed a laser-like weapon to defend themselves.
TO FACE A MONSTER by Carl Henry Rathjen
A boy with with an inferiority complex due to his small build proves his mettle and saves his uncle's life by standing up to a fearsome forest creature that resembles a large dog.
YOU ARE WHAT YOU EAT by Wilma Bednarz
Between the title and the giant wasp pictured, you might think this is some new version of H.G. Wells "Food of the Gods". But its really just a basic alien invasion story. A U.F.O. lands and the giant wasp is actually the shape assumed by its alien pilot. The alien doesn't like noise and so the boy in the background is making as much clamor as he can.