I don't think it's a realistic option if you want to crop your plants within your lifetime because even if you were to plant an apple pip, a seed or a nut kernel it would be many years before your plant/tree would bear a satisfactory yield. Also, many fruit trees are grafted onto specific rootstocks and anything you planted might not come up as a "true copy" of the original plant. A couple of years ago, I planted a couple of sweet chestnuts in pots because the tree they came from was going to be chopped down.. The seedlings are now about ten inches high and I reckon that if I planted them out into the ground it would be about 25 years before they cropped any nuts. I think the only realistic option if you want to grow these plants is to get them from a garden centre or nursery, although if a friend grows strawberries, you might be able to persuade them to give you some free "runners" from the plants which have been potted up.