Insect and Spider Identification: Insect eggs?, 1 by Pandafish

Pandafish wrote:
I found these on my patio umbrella, which had been folded up and left outside for about a month. I presume they are some sort of eggs, but I have no clue what. I scraped them off because I wanted to clean the umbrella, so waiting for them to hatch is not an option. They were hard, very resistant to being scraped off, and left tracks behind. It seemed like there was nothing inside them, but what can they be but eggs????