My Ideas for additional trinket effects:
Sigil of Baphomet: Shield lasts longer
Flat Worm: Extra tear width
Tonsil: Greater chance to spawn a tonsil familiar
Broken Magnet: Stronger pull
Friendship Necklace:Familiars circle around closer to the player

This mod is absolutely fan-♥♥♥♥♥♥♥-tastic. I really don't know why this isn't in the base game, but it's definitely earned a permanent place in my mod-list. Here are some Ideas for the remaining trinkets.

Brain Worm - Increase the range at which the tear redirects by 50% of base
Broken Magnet - Each additional broken magnet gives a chance to instantly collect each
pickup in the room (Each pickup rolled separately)
Broken Padlock - Grants an additional pickup for every destroyed lock
Butter! - Spawns a slippery pool of butter that damages enemies. Damage and size
increase with more trinkets
Crow Heart - Damage to red hearts has a chance to be blocked (like Mask of Infamy)
Cursed Skull - Has a chance to trigger glowing hourglass instead
Devil's Crown - Causes the item to switch between two, like Tainted Isaac / Gives a
chance for devil deals to be free
Door Stop - Chance for additional doors to open on first visit to any room (Maybe even
small chance for red doors)
Duct Tape - Creates a "sticky tape" (recolored laser with slowing effect) between Isaac and
his familiars. Beam deals a fraction of his damage
Equality! - Picking up a consumable gives a chance to give an extra consumable of the
lowest amount Isaac has
Flat File - Each removed spike has a chance to spawn a small, highly damaging pool of
friendly blood creep
Flat Worm - Small chance for tear to have rubber cement effect and extra knockback
Friendship Necklace - Familiars orbit faster, and get a small damage buff
Mom's Toenail - Foot stomps more frequently, has a chance to not stomp if it targets Isaac
Mysterious Paper - Chance on hit to be destroyed and drop a paper themed item (Coupon,
steam sale, the pact, prayer card, ect.)
Nuh Uh! - On all floors past womb, has a chance to spawn a copy of each pickup
Ouroboros Worm - Tears gain small homing effect, increases with more trinkets
Pulse Worm - Larger max size of the pulses / Causes damage to fluctuate with the pulses
(+0.5 to -0.5 per trinket)
Rainbow Worm - Triggers 1 additional worm effect per trinket.
RC Remote - Familiars deal contact damage / Familiars gain increased fire rate
Ring Worm - Gives a shot speed down/range up effect, giving tears more time to circle around and hit an enemy
Safety Scissors - Gives a chance for bomb to be upgraded (Regular bomb > Double Bomb
> Mega Bomb > Golden Bomb) / Gives a chance for a diffused bomb to trigger Mama
Mega for that room
Sigil of Baphomet - Each kill gives a small temporary stat-up that expires when the
invincibility ends
Store Key - Opening a shop gives a small permanent stat up / Gives a Large temporary
stat up (like red stew)
Tonsil - Increases chance of tonsil spawning, and gives additional tonsil

'M - Your Spacebar item gets re-rolled automatically every 30 sec. Each additional trinket halves the time it takes, possibly with a hard cap of 1 second minimum

Originally posted by axfty:

Store Key - Opening a shop gives a small permanent stat up / Gives a Large temporary
stat up (like red stew)

I really like the permanent stat up idea, I just implemented it, and it will be in the next update :).Some of these other ideas would be hard to do with the current modding api but Ill look into some of them. Also thank you for the kind words

Butter! - Getting hit WILL drop the last item isaac picked up
Cursed Skull - Teleport you to the I AM ERROR ROOM if the hit would've killed ya
Mom's Toenail -Mom's foot will target tinted rocks and secret rooms entrance
Flat File - Spiked / mimic chest can now contain items
Friendship Necklace - Familiars that do not normally block shot will block shots
Devil's Crown - Devil's item rooms now use the same layout as the number magnet trinket
Lucky Rock - Stoney / poki type enemies now drops coins when the room is cleared

Here are my ideas:
Brain Worm: Increased range and gives spectral tears
Devil's Crown: The red treasure rooms will also have 1 black heart
Mom's Toenail: Mom will target the enemy with the most HP instead of a random location
Found Soul: Found Soul will have holy mantle by default (Will have 2 shields if you also have holy mantle)
Gilded Key: Chests can have 1-3 more pickups (Weaker mom's key)
Butter!: Getting hit is guaranteed to drop items, prioritizes lower quality ones
Broken Padlock: Exploding locks has a chance to drop keys
Crow Heart: As long as you have soul/black/rotten/bone hearts, taking red health damage will not lower devil/angel room chance
Lucky rock: Pennies dropped by destroyed rocks have a chance to be chests instead
Sigil of Baphomet: Also grants a small temporary damage up on killing enemies
Tonsil: Tonsil familiars will pull in projectiles like Forgotten in soul mode
Keeper's Bargain: 15/30 coin devil deals will cost 3/6 less coins
Extension cord: The lightning will do more damage and also homes in nearby enemies (Like Jacob's Ladder)
Friendship Necklace: grants a very weak version of The Mind, becomes stronger the more familiars you have
Missing Poster: Using a sacrifice room has a chance to drop a soul heart
Adoption Papers: Chance to reroll low quality familiars
Mysterious Candy: Chance to spawn golden, rainbow or holy poops

Worms: A small tears up for all worms
Nuh UH: When a coin or key is replaced double the drop
Door stop: Open all doors like mercurius
Sigil: 2 sec shield instead of 1
Mysterious paper: the cycling of items actually does 2 at a time
Equality: Items can differ for 2
Flat file: Also works on creep
Devils crown: Choice item rooms with hidden pedestal
Other crowns (i know you have them already but whatever ;) ) : Choice item rooms with hidden pedestal

Butter is a food item, so maybe its stacked version could have an effect relating to health? Like 'on hit, 5% chance to drop a heart pickup'.

Stacked store key is easy though - all stores, item rooms, and special rooms are unlocked.

https://steamhost.cn/steamcommunity_com/sharedfiles/filedetails/?id=2509152501
Gold Isaac's Head isn't stacking as expected, shame.
E: It spawned ... after an entire floor. Seems like it was because i swallowed it

Originally posted by Beginners (but not a N00b):

https://steamhost.cn/steamcommunity_com/sharedfiles/filedetails/?id=2509152501
Gold Isaac's Head isn't stacking as expected, shame.
E: It spawned ... after an entire floor. Seems like it was because i swallowed it

Ill look into it later this week, sorry about that

Originally posted by edinefin:

Originally posted by Beginners (but not a N00b):

https://steamhost.cn/steamcommunity_com/sharedfiles/filedetails/?id=2509152501
Gold Isaac's Head isn't stacking as expected, shame.
E: It spawned ... after an entire floor. Seems like it was because i swallowed it

Ill look into it later this week, sorry about that

Don't worry about it. It's still better than anything officially implemented so it's a win in my book.

A bit off-topic, but maybe it's better to remove trinkets from the list for which effects have already been invented?

Originally posted by De(ad)orion:

A bit off-topic, but maybe it's better to remove trinkets from the list for which effects have already been invented?

Just updated it to remove the already implemented trinkets.

Bob's Bladder > Much bigger pool / Pool freezes like holy water
Eve's Bird Foot > 10%
Broken Magnet > becomes same as magneto
Butter! > Dropped item has a chance to start cycling like tainted isaac
Cursed Skull > Heal 1 HP after teleporting
Devil's Crown > Judas tongue effect / More options effect
Door Stop > Leaving room through the open door has a chance to activate glowing hourglass
Duct Tape > Small tearsup for familiars
Flat File > also creep
Friendship Necklace > Small tearsup for familiars
Mysterious Paper > Cycle has 2 at the same time instead of 1
Nuh Uh! > Replaced pickups get doubled
RC Remote > Small tearsup for familiars
Sigil of Baphomet > 2 sec shield instead of 1. Might be OP so 1.5 is also possible
Tonsil > double spawn chance / Limit to 4

Crow's Heart has a typo in the EID description. It says change to convert... when it should say chance to convert...

Eve's Bird Foot > Spawns an extra bird when only one would spawn (Like how ???'s Soul currently works)