Please try this basic troubleshooting:
Clear your browser and flash player caches.
Update your flash player manually. This means download the update then instal it, not letting it automatically update. Also make sure any software that uses flash is updated as outdated software can interfere with your flash player.
If that does not resolve the issue of crop seeds not showing in your inventory please fill out a ticket http://www.aeriagames.com/contact/support
and describe your situation and what you have tried already to resolve it.