True coffee is made from coffea arabica, a tree or shrub that produces coffee beans (seeds), but there are other drinks that are called coffee, too. They're made from grains, which are seeds, and they're roasted and ground in much the same way.
You can make these coffees or drinks easily at home. The grains, barley, rye and others, are easily found if not in a grocery store, then in a health food store.
Grains like these don't contain caffeine and they don't taste like Coffea arabica, but they have their own charms.
To make barley coffee, put a tablespoon or so of barley grains in a medium hot skillet and stir often until the grains are toasted a medium brown. You may prefer them lighter or darker, but start with medium.
Once the grains are toasted, pour them onto a plate and let them cool. Put them through a coffee grinder just like you would coffee beans. Use any kind of coffee maker you have to make the barley coffee. It won't be as dark as regular coffee.
The same method can be used for rye or okra seeds. (Don't use okra seeds you've bought for planting as they may have antifungus powders on them.)