You are dealing with exempt items. At first look you do not require GST registration, however before coming to any conclusion based on 2 facts, lets analyse few rules which mendate GST registration.
- Trunover cross 40 lakhs (It includes both taxable and non taxable items), so if you are even selling a single taxable items, you need GST registration since your turnover is more than 40 lakhs.
Now, coming to your specific points:
- Growing mushroom is agriculture activity and is exempt from GST. Since you are selling in raw form, GST is not applicable.
- Poultry Feeds is exempt from GST.
I will suggest to share a complete list of item, you deal with. Even if a single item is taxable, you need to get registered under GST. But if you are dealing on in these 2 items, you need not to get registered.