They say the world is round, but I am flat. What am I?

A guardian of doors, resting with grace, Keeps secrets safe, in their rightful place. With a gentle click, it holds the line, Securing the world with a silent sign.

I am a sugary ring with a hole at my heart. Glazed goodness - a lovely work of art. Paired with your coffee, I play the sweetest part. Take a bite and happiness will start.

Deep in the soil, I slumber and grow, A ruby-hued treasure that few truly know. Earthy and bold, I color your plate, A hidden delight, both hearty and great. What am I?

I stand in a wall, yet I’m never quite still, I let in the sun, yet I bend to your will. I frame the world, though I hold no brush, I can open to chatter, or silently hush. What am I?