Mindfulness lies in all the senses. Through the senses we are able to be aware of something and thus know something at all. Clear hearing, clear feeling of smell, taste and touch. Clear knowledge of what you are thinking and what emotions you are experiencing. A grounded feeling in the body for what you are feeling, whether it be fear, impatience, joy, empathy or whatever. In this way, anything - a gentle caress of the wind, a play of light and shadow, someone's facial expression, a momentary contraction in the body, a fleeting thought - can become our teacher in the moment, reminding us of the possibility of being fully present. As long as we meet it with a conscious mind.
For mindfulness is consciousness of mind - "that which occurs when we give attention to something intentionally, in the present moment, without judgment and as if life depended on it." Jon Kabat-Zinn