For me, getting outside. I agree with fern on touching the Earth, using hands (gardening or otherwise), feet (the most grounding from bare feet). It can also be helpful to rest with your spine against the ground and/or your knees up and feet flat on the "ground'" Another method I have read about is to stand with your spine against a tree: trees are very "grounded" with their deep roots into the ground.

I agree, a walk in nature can be helpful. A "walking meditation" might also be helpful.

Breathing exercises can often bring me into the Present Moment quickly. If more help is needed in order to pay attention to the breath, try Thich Nhat Hanh's method of describing what you are doing: "Breathing in, I know I am breathing in. Breathing out, I know I am breathing out."

His teachings for anchoring into the Present Moment include things like: When the phone is ringing and you are responding to answer: Answering the phone, I know I am answering the phone, for example. If one tends to need more grounding at anytime and/or throughout the day, this can be helpful, going through your day being very mindful of whatever you are doing, anchoring into your body and into the Present Moment. This can be especially helpful for people who tend to dissociate.

Foods: I again agree with fern. Usually higher fat foods, maybe higher carb foods and root vegetables. A very spicy or a pungent food might help with grounding. A very cold drink might help. These more extreme types of sensations can be grounding.

Strong odors can help. Which odors do you find strong, maybe even offensive?

Look around the room and name 10 things in your environment. May help more if you also involve a description: A tall red rose, a long-haired brown cat, a rectangular birch wood desk, long green heavy drapes, etc.

A hand full of ice cubes can be grounding.

I have found if I have been alone, starting a conversation, as in talking out loud with another person can help. This can be on the phone, skype-like settings, etc.

Loud music might be grounding. it really depends with music and the individual. Some music can unground me.

Some may feel grounded by weighted blankets.

Some find bodily sensations help with grounding. Maybe a massage, exercise...

Interestingly, there are "grounding sheets" (for beds) and grounding mats, even grounding mouse pads.

Just a few ideas off the top of my head.