In basic motor and generator theory examples (many online) current passing thru a conductor located within in a magnetic field/influence, or a conductor moved thru a magnetic field are the basic principles. Finding descriptions of how automotive alternators shouldn't be difficult, and will likely explain a lot wrt generation.
Many generators utilize brushes, but induction motors can generate under the proper conditions, as in Winston's referred example.
IIRC, the automotive generators of old cars utilized poles within the stator/field windings, (and brushes).. the poles weren't permanent magnet material, but they would hold in a magnet-like state after being properly magnetized.. same/similar to Don's example. If you can refer to an older automotive service manual (pre-1970s), you'll likely find the procedure to stun? the pole pieces in those old generators.
A very weak/slow-motion motor example would be analog panel meters. In the moving coil type meter movements, the coil (armature) is supported on low friction pivot points (were jeweled bearings in days of old) within a magnetic field. When an appropriate small current flows, the meter needle deflects, and if the moving coil is rotated manually (not a normal procedure), a small current flows. Many new analog meters are packaged with a shorting wire across the terminals to dampen the needle movement during shipping.. an example of braking of the generator effect. Not all analog panel meters employ moving coils, though, and those which aren't, don't effectively generate any current flow.
Over the years, I've seen a lot of DIY websites showing various generating techniques from portable/emergency power to wind generation generators that were made in home shops with powerful magnets (surplus suppliers) and hand-wound coils on forms and later potted in epoxy or resin.