I found this rock on the shore of the Kennebec river while fly-fishing. It had some striations, so I split it and voila! Some of the shells had not fully mineralized.
Here is fossilized stuff from the sea-bed in a matrix of limestone. I don't know what all that stringy-looking stuff is, but I assume it could be the remains of sponges, corals, etc. This rock came from the causeway between Clearwater and Tampa.
Another rock from the same causeway, except this one has a brilliant geode-like cavity.
Not a fossil, but a very interesting boulder. It consists of lepidolite (purple matrix) with cleavelandite (white feldspar) and red and blue tourmaline. This rock weighs well over a hundred pounds, and I carried it nearly 1/2 mile to my truck. I found it in the tailings-dump of a beryllium mine in western Maine. The mine was opened to provide beryllium to the weapons industry after Germany had cut off supply-lines from Africa in WWII.
Last, here is a boulder of jasper that I found partially exposed in a stream. It took me over an hour to dig it out, and a friend and I needed over 1/2 hour to get it up the bank to the road. It weighs probably 300 lb or more.
I've got LOTS more minerals and fossils, but these are the ones currently displayed on the front patio. When we sold our last place, I had to leave many hundreds of nice rocks - no place to put them all. I had bordered flower gardens, walks, etc with them and didn't want to tear all that up.