In researching family trees and regional history I will sometime go to cemeteries to look for a grave. Usually if I find the grave I try to photograph the headstone. Some of these markers and headstones are overgrown with grass, and sand has covered part of the marker. To handle that problem I carry with me a cleanup kit, of whisk brush, spray bottle of water, cleaning rag, grass clippers, and an old butcher knife for outlining the marker. In cleaning up the marker I have found an assortment of items left behind by the grieving to show respect for the person. I leave them there, only moving them around to get the photo and then place them back where they were. Now it is not up to me or anyone else what is placed on a grave. Whatever people want to leave as a measure of their grief is up to them. I will say I have seen a large increase in the amount of material put on graves in the last 50 years.
The most common items I find on graves are plastic flowers, solar lights and wind chimes. Smaller items however are stones, coins, matchbox toys, stuffed animals, golf balls, pencils, military ensignias, bullets and sea shells. The ones I find interesting and scary are the jars.
When I first started looking at graves on rare occasions I would find the old mayonnaises jar with the lid on it and a letter or note inside. Since I was doing research I thought it might be a note from another researcher asking for information or giving family contact information. One time I found a note like that, the other three times were very bitter letters sent to the deceased. I now leave any jar with a note inside alone and untouched by me.
The other form of gravestone jar is what I call spell jars. I have found maybe three of these type jars on graves over fifty years and at least one had animal bones scattered on the grave also. The jars appear to have fruit, keys, nails, and coins inside them. I have no idea why they were put there nor do I know what their true purpose is. I assume someone had cast a spell using the jar either on the deceased or using the grave as a transmitter to someone else. Anyway I leave the jar alone. Let the cemetery maintenance person worry about what to do with it. The couple of photographs I had of these spell jars were destroyed in a house fire. I will put this photograph found on facebook as an example of a spell jar.