Inspired by FenixR's upgraded machines, I decided to make upgraded Seed makers. I wanted something that gave a set amount of seeds but wasn't too cheat-y, so I made my own.

Iron gives 4 seeds per crop
Gold gives 6 seeds per crop - needs 1 fiber
Iridium gives 8 seeds per crop - needs 2 fiber

Requires CustomFarmingRedux - If you're using the most up-to-date version of CFR (2.10.4), add the machine folder to your main Stardew Valley mod folder.
For older versions of CRF, make sure you use the older versions of this mod for it to work.

Iron seed makers require 25 wood, 2 iron bars, 2 gold bars, 10 coal; Gold seed makers require 25 wood, 4 gold bars, 4 iridium bars, 15 coal; and Iridium seed makers require 25 wood, 5 iridium bars, 5 prismatic shards and 15 coal.

I have included iron, gold and iridium makes for the default crafting set and for Eemie Darker Craftables, so you can pick depending on what set you're using.
Just make sure to change the picture name so it reads as like - IronSeedMaker GoldSeedMaker IridiumSeedMaker

18/08/18:
Now contains support for crops from Farmer to Florist, Fruit and Veggies, and Mizu's Flowers. (As per vanilla, you can't use the seed maker for any crops that come from trees - but if anyone would like that added, I can add an optional file for you)

19/08/18:

Couple of bug fixes-incorrect crafting requirements for Iridium maker
  ancient seeds now actually stack properly with seeds made from the recipe
21/08/18

Added Garlic as I forgot it initially ^^

02/09/18

Fixed Artichoke's not working
Added support for Fresh Meat.

23/12/18

Updated version to work with updated CFR.

I have uploaded two versions, one with just vanilla seeds and one with the support for extra crops - USE ONLY ONE OF THESE!