Top one is Navy, Third is Artillery and the last is the backside of s flat button. Are there any backmarks on the first four buttons? And are they all one piece buttons?If so, they pre-date the civil war and are most likely from the 1820s-early 1840s.
Can you tell us where they were found? In general..not your spot or anything. I would expect you will find... musket balls.. Flint..clay pipes..and black glass in that same area.
Sounds like a good spot. If there is water and its not a dry river bed sifting might turn up some nice non metallic items like kaolin pipes...flints..ect.. look forward to seeing your finds. I will post some of mine tomorrow. I'm usually on the Indian artifacts forum but I do alot of hunting.