J.J.Thomson in 1897. In experimenting with a Crookes, or cathode ray, tube, discovered the electron. He showed that cathode rays were charged negatively. Thomson discovered that negatively or positively charged particles were not provided for by the agreed model of an atom.
The electrons, like the metal that goes through the wires, or the atoms in batteries, come from material artefacts. Electrons contain all material objects. If they are useful for electricity as a supply of electrons depends on the substance.