What's better, a lump of gold or a puzzle to be solved? Rusty objects are a challenge.
The horseshoes are the only immediately recognizable items. The two older ones have a calk that might be a clue to age or use -- maybe the horses/mules were worked in beach sand and that's why the calks. The newer horseshoe looks machine made.
The nails/spikes can be dated to an extent by inspecting them closely to see how they were made and how the heads were shaped. Google for info on dating nails and spikes.
The big tripod thingie with the hex nut is relatively modern, prob since the 1880s. What was it? I'd get hold of a Sears Roebuck catalog circa 1902 (a lot of them are reprinted) and see if it is identifiable there -- some kind of mill or bearing is my guess.
What's that boot shaped rock?