Video-game Add-on: A small device which when plugged into a video-game controller, probably in the headphone jack or something kind of universal between types of video-game controllers will influence any game played with it, turning it into a "haunted cartridge creepypasta" style version of itself. Sort of a universal explanation behind "haunted video-games" creepypasta SCP style. The game may show signs of sapience against the human playing it, such as enemies looking like people the player knows, or speech being changed so it tries to talk to the player.
Questing Beast: An animal with a weird effect based on the Questing Beast of Arthurian legend. The more people know about it, the less likely they are to come across it. Uncontainable as simply telling a foundation agent "this is what it looks like, now find it" means that they never will be able to do either. The foundation simply goes around amnesiac-ing citizens who see it.
Gremlins: A bunch of tiny self-replicating-machine drone aircrafts. They fly in swarms and hunt by setting down on an airplane, pulling off parts and assembling them into new "gremlins." Odd in that by all rights their designs shouldn't work. They lack a fuel source. They lack motors. Their propellers aren't big enough to get them airborne. They just look like someone sculpted a load of broken airplane parts into tiny flying robots… ….but they work. Foundation attempts at taking aircraft parts and assembling identical machines fail to do anything.
Defended Tree: A tree, possibly of a species as it flowers, which produces odd knotholes of wildly differing sizes all over its bark. Whenever anything attempts to harm the tree the knotholes "unfold" ejecting the "defenders." Odd creatures which basically consist of mobile plant-tissue sculptures with insides built like animals, for example one might have grassy leaves for fur, berry-like sacs for eyes and organs and a wooden skeleton. Said defenders will attempt to drive off whatever creature did the attacking. If it wins the fight, it either crawls back into the knotholes in the bark, or just drops dead next to the roots. Species imitated in appearance by the defenders depending on what creature was attacking the tree. For example, an ant would simply get some kind of wooden lizard which would eat it smashing it to bits, whereas an unarmed human would get a wolf or something and an armed foundation MTF containment team [DATA EXPUNGED] loads of deaths.