Spore Shrooms

Drop: Rotcap [30-40]

Zone: Spires of Arak

Drop Rate: 1 in 1

Vendor: Jenoh

Zone: Vol'dun

Cost: 150 (unlimited supply)

Vendor: Madeline Netley

Zone: Stormsong Valley

Cost: 150 (unlimited supply)

Drop: Strange Spore

Zone: Gorgrond

Drop Rate: 1 in 1

Pet Battle: [25] Zaralek Cavern

Quest: Pet Battle Challenge: Wailing Caverns [45]

Zone: Northern Barrens

Drop: Damp Pet Supplies

Approximate Drop Rate: Unknown

Drop: Loatheb [??+]

Zone: Naxxramas

Approximate Drop Rate: 1 in 7

Vendor: Tiffy Trapspring

Zone: Lunarfall

Cost: 100 (unlimited supply)

Vendor: Giada Goldleash

Zone: Frostwall

Cost: 100 (unlimited supply)

Pet Battle: [25] The Ringing Deeps

Drop: Karokta [??+]

Zone: Zaralek Cavern

Approximate Drop Rate: Unknown

Drop: Fel-Touched Pet Supplies

Zone: Tanaan Jungle [40]

Approximate Drop Rate: Unknown

Pet Battle: [25] Talador

Pet Battle: [25] Zaralek Cavern

Vendor: Trading Post

Zone: Orgrimmar (H), Stormwind (A)

Cost: 200 (unlimited supply)

Pet Battle: [18-19] Zangarmarsh

Vendor: Mycah

Zone: Zangarmarsh

Faction: Sporeggar - Exalted

Cost: 30 (unlimited supply)

Pet Store 

Drop: Strange Spore

Zone: Shadowmoon Valley (Draenor)

Drop Rate: 1 in 1

Drop: Fungarian Delve's Heavy Trunk

Approximate Drop Rate: Unknown

Drop: Fel-Touched Pet Supplies

Zone: Tanaan Jungle [40]

Approximate Drop Rate: Unknown