Attaching media files is bit confusing but here are some steps which will help you to easily app attach files in mail app
Step 2: Then fill the Email id and subject
Step 3: Then tap below the subject space this will give you a pop-up menu
Step 4: – Then click the white triangle symbol it will give you some more options.
Step 6: Just tap one more time on white triangle it will give you Add Attachment option