Yarn

 Starting from minecraft 1.14 this mod was rewritten as datapack:

v1.14+ on Google Drive

v1.16 on Google Drive

v1.17 on Google Drive

v.1.18 on Google Drive 

v.1.19 on Google Drive 

v.1.20 on Google Drive 

v.1.20.2 on Google Drive 

v.1.21 on Google Drive 

There is no need to kill to get your ball of yarn.

If you play on peaceful — this mod is for you!

If you are afraid to go outside at night — this mod is for you!

If you don’t like or don’t want to kill monsters — this mod is for you!

Yarn allows you to craft items that otherwise are only available from monster drops.

With yarn you can craft:

• string (from wool — hence the name)
• rotten flesh
• gunpowder
• slime ball
• spider eye
• saddle (versions 2.1.1+)
• any horse armor (versions 2.1.1+)
• name tag (versions 2.2.0+)

After you visit Nether you’ll be able to craft:

• ender pearl
• blaze rod
• ghast tear

After visiting the End you’ll be able to craft:

• skeleton skull
• wither skeleton skull
• zombie head
• creeper head
• nether star (versions 2.3+)
• shulker shell (version 2.4+)

Use JEI or NEI or whatever to get recipes.

P.S.

You may use this mod in a modpack as long as you do not make money off of it (Adf.ly, exclusive access from donations, etc.), you give credit (Linking back to https://minecraft.curseforge.com/projects/yarn) and you follow all the terms listed in the license.

I would appreciate if you notify me prior to inclusion the mod in a modpack.