Homemade masonry questions..

I've gotten tired of banging a freshly sharpened spade against buried rocks and such in my garden beds, so I'm slowly digging them out to 3'+, and removing anything over 1/4" diameter and hard.

My land was apparently reclaimed from salt marsh by piling up sand, followed by busted up rubble like roadbed, concrete, asphalt, bricks, clay drainage tiles, potato rocks and all sizes and shapes of gravel. The top layer is 1-2' of stuff dredged out of the bottom of the canal, which has become very nice sandy loam.

I'm gradually building up huge piles of this stuff, and I'm looking for something to do with it. For example, I could use nice blocks to outline garden beds, and to build raised beds.

Is it possible to use this rubble as coarse aggregate in some sort of masonry mix, and to mold said blocks?

What mixture of Portland, etc. would be appropriate for such purposes?

One more question...living on the edge of a bay, I have almost unlimited access to sand. I can dig it out of my yard, or swipe it from numerous sandbars and beaches. Will this scavanged sand work in concrete/hypertufa mixes?