Enable the Flower Background in Your Inventory
Activate the Resource Pack
The Flower Inventory Background is a resource pack, so it must be enabled through Minecraft's resource pack menu rather than installed as a mod.
1. Open Minecraft and go to Options → Resource Packs
2. Look for "Flower Inventory Background" in the available packs list on the left
3. Click the arrow icon to move it to the Selected section on the right
4. Close the menu and return to the main screen
Verify It's Working
Once activated, open your inventory. You should see a decorative floral pattern behind your inventory slots instead of the plain vanilla background. The flowers will appear on the main inventory screen, crafting table interface, and other menu screens.
If you don't see the flowers, make sure the pack appears in your Selected list and is positioned above any conflicting packs. You may need to close and reopen your inventory for changes to take effect.