When I began living without money 18 months ago, the most common question people asked me was "How on earth are you going to eat?". An understandable remark, but an insight into the burgeoning degrees of separation between the stomach and the soil.

For most of us, food comes in plastic packets from the supermarket. A friend, who runs tours of an organic farm for school children, gives much anecdotal evidence of this. One week, while pointing to a rosemary bush, he asked the kids if anyone knew what it was. After 20 seconds, one 12-year-old raised his hand and proclaimed it to be "corned beef". Worse still, none of the others laughed.

The answer to this FAQ is in the query itself – I eat from the earth. Food is free, and indiscriminately so. The apple tree doesn't ask if you've got enough cash when you go to pick its fruit; it just gives to whoever wants an apple. We are the only species, out of millions on the planet, that is deluded enough to think that it needs money to eat. And what's worse, I often observe people walking straight past free food on their way to buy it from all over the world via the supermarket.

There are four legs to the money-free food table. The most exciting, and my favourite, is foraging, which originally meant to wander in search of food and provisions, but is used these days to describe the act of picking and eating wild foods. Although this can take a lifetime to learn, anyone can start today. I'd recommend picking up a pocket-sized book called Food for Free by Richard Mabey (sourced for free via Read It Swap It) or perhaps taking a weekend course with people such as the BBC's "roadkill chef" Fergus the Forager, before hitting the hedgerows.

At the moment look out for giant puffballs, bristly ox-tongue and rocket, the latter often found in the cracks between walls and paths in cities. If you need any more excuse to hit the coast, now is the perfect time to collect seaweed. The real beauty of wild food is not only that it's highly nutritious and ecologically sound, but that picking it is also a fantastic excuse to go adventuring with friends.

Great Britain has been tamed, so its remaining wilds could no longer feed its population. This makes the next leg – growing your own food – crucial, both in terms of tackling climate change and rebuilding a resilient local food network. Whether it be on your kitchen windowsill, in your back garden, or on the allotment, start with whatever you can manage. Choose crops you love eating and if you are time poor, choose varieties that require little work. Not only will you reduce your food miles and packaging, you'll also get to eat food that tastes of your own sweat, a flavour no spice can match.

Growing and foraging all your calorific needs is a huge task, especially without fossil fuel inputs such as fertiliser. This is where the third leg comes in: bartering. Bartering can either be an exchange of food, especially in the summer when many people have gluts of one crop or another, or an exchange of skills for food you can't get elsewhere without money. In many ways barter is just an awkward form of money and lacks the deeper benefits of doing something completely for free (such as you do with close family and friends), and it brings up the age old problem of "the double coincidence of wants", where both parties have to have something the other desires. But it has got huge benefits. Not only does it localise the economy, it helps build bonds between neighbours, leading eventually to communities that are more resilient to external shocks; societies where friendships, not cash, are seen as security.

The fourth leg of the food-for-free table is waste food. Skipping – jumping into skips – is one form of this, but I prefer to build relationships with small businesses that throw perfectly good grub away, either because of insanely rigid laws or their own quality standards. By choosing this method, you save yourself the task of looking through a bin and you get to build a relationship with another local who, in almost all cases, feels terrible about chucking out edible food (one third of all food in UK is wasted) at a time when one half of the world's population goes hungry. Whilst I don't tend to eat much waste food myself – it makes up roughly 5% of my diet – I do go skipping regularly. It's a lot of fun and I distribute the harvest to those who need it. Using waste food is far from ideal, as it is hardly building a sustainable model that the rest of the population could replicate. But while we continue to fly food from all over the world just to make it into a UK skip, I feel our first obligation, to both the farmer and the hungry, is to get it out of bins and into bellies.

So Milton Friedman – if the Guardian is available online beyond the grave – I hate to break it to you, but there is such a thing as a free lunch.

• Mark Boyle is the founder of the Freeconomy Community and has lived moneyless for the last 18 months. His book, The Moneyless Man, is out now, published by Oneworld - sales from the book will go to a charitable trust for the Freeconomy Community