Hello. Looks like "Patina " . Worth about a dollar but don't go trying to buy a Mcdonald's Dollar menu item. IMO
I agree with @SensibleSal66. Place it in a 2x2. Eventually over time, if left to the elements, your whole cent will turn green. According to Corrosionpedia, "Oxidized copper is a specific type of corrosion that is produced during a three-step process. Copper oxidizes to copper oxide, then to cuprous or cupric sulfide, and finally to copper carbonate. It results in a green-colored copper layer or patina that forms over time." It's like the green you see developing on copper plumbing pipes.
That is a 1928 Large S cent. The small 'S' is most common and is referred to as the regular 'S' mint mark. The Large 'S' mint mark is very scarce compared to the regular "S" mint mark cents. Value will depend on the buyer.
It has retoned colorfully after being cleaned. That toning is secondary toning, and would be considered a "problem" by a third-party grading company (not that you'd want to waste money sending such an inexpensive coin off to be graded anyway). That being said, though it's not considered "original" toning, the colors are kind of attractive. Though it likely happened through natural means over time, this kind of secondary toning is considered "artificial" toning in the marketplace, since it happened as an after-effect of someone harshly cleaning the coin. It's no slab/certification candidate, but it's a perfectly acceptable coin to put in a folder or bookshelf album. In fact, it is probably got that toning from being in such an album over a long period of time.
