OP here. The instability of the umbrella was due to my husband cutting apart the stabilizing framework under the table that would normally keep this kind of thing from happening because he bought me a "much more awesome" umbrella that was too big for the table. He had good intentions, but I had a feeling the cutting of the framework would be a problem later. And no, there will most definitely not be a next time. As for vacuuming it up, maybe so, if I had a shop vac. As it was, he had loaned our shovel to a friend, I had no gloves, and the grass was long. I improvised and ended up using a hoe and two dust pans. It worked.