Get yourself a shell sifting basket like they sell on the coast for collecting shells or sand fleas. Go down to the old boat ramp at Montverde on the west shore of Lake Apopka. Get some Hefty yard bags, put your foot into one and slide into a good wading shoe then duct tape them into a cheap version of hip wader. Lake Apopka is polluted even though a restoration project is making the water cleaner. Wade out from the ramp and start scooping the bottom into a floating sifting box. Its back breaking work but it can be rewarding. Lake Apopka had a large Indian population for hundreds of years. And I've seen beautiful arrowheads and spear points that came from the lakeshore over the years. Try some of the farm fields between plowings on CR 448A/ Duda Road, be sure you get permission.
Good Luck.