do you return key board and Mouse when recycling computer?

Apple's instructions will tell you to only return the Mac and its power cord.

Source?

The Apple Recycling Program will:

• Responsibility recycle your Mac
• Offer credit toward a purchase

Simply follow the instructions included in your trade-in kit. It explains how to prepare, pack, and ship your device.

Although you don’t need to include any of the included accessories, the value of the gift card has traditionally been based on the included accessories. 

For an iMac, I have always included all hardware.

For Mac mini, I kept everything.

You should be good to go‼️