Ceramic shards in the Field

We like to walk the perimeter of our eight acre property in the evenings. Sometimes, usually after a good rain, we'll go to the row of young live oaks or the parish ditch on the east of the property where there is a concentration of glass and pottery shards. We find what seem to be old ceramic or stoneware pots, crocks, and cups and plates made of milk glass. We usually find white, in all shapes. They come with beautiful angles, all a little different with no exact matches in quality or shape. Sometimes we find blue designs on them, old and new, or a piece of what seem to be the decorative curl of a fleur de lis. Sometimes there are chunks of thick pottery white on one side, black on the other and made of fine cement-like material. This area in general has been inhabited by French Creole settlers since well before 1800, and before that the Opelousa Indians rested here when hunting in the oxbow swamp. When we moved here, it had been a sweet potato field and let to go fallow for years. So how old are these shards? Were they left from trash dumps behind houses? Brought by flood? Used by farmers to aerate the field? Why are they all different, yet concentrated in one area? Were there houses all the way back here in our field, long ago? For now we'll keep filling mason jars with them as we try to piece together the jigsaw of PDF history they have revealed to us.