I've been working on this off and on for the last 2 years and finally got the first version finished! You can find the Hybrid Cowberry in Appliances > Fridge or in the catalog by searching 'garden' with the bb.showhiddenobjects cheat active. I'm working on a mod right now to make my harvestables more accessible :)

This mod makes using cowplants more fun and functional to grow. You can interact with the new Hybrid Cowplants like you would with the original cowplant, but when you do it will effect your relationship with them. Certain interactions will improve your relationship (petting, playing with) and others will hurt it (fattening it up, milking it). 

You can feed Hybrid Cowplants several types of food which will make their udders full and ready for milking. Each type of food will effect the Hybrid Cowplant differently. Just remember Cowplants are carnivorous by nature, they'll eat scraps if they have to but they prefer to have meat!  

Hovering over the cowplant will show your sims relationship with it as well as it's hunger and health. Be aware that their health and the sim's relationship with them will effect the quality of milk products you get!

Cowplant Milk Health Reference:

• Flourishing - 3 bottles of milk

• Vibrant - 2 bottles of milk

• Good - 1 bottle of milk

• Bloated - 1 bottle of milk & 1 bottle of cream

• Queasy - 1 bottle of sour milk

• Sick - 1 bottle of spoiled milk & a random alien seed

The hybridization process has imbued these plants with sim-like empathy so if a sim happens to get eaten, they have a better chance at surviving if they're friends with it.

You can also graft the Hybrid Cowplant onto other plants. You may even create some new Hybrids if you graft it to the right plants! 

At a certain friendship level you can choose to 'Clip Tendrils' from the cowplant. These can be used as an ingredient in recipes that are coming soon!