When my old picnic rug fell apart, I started looking for a new picnic rug and my only two requirements were that it must be water-resistant and contains NO PVC (the most toxic plastic). Unfortunately, I had a really hard time finding one and so we have lived without picnic rugs for almost a year until I came across this great Canadian company who makes water-resistant outdoor gears that are PVC-free.
What makes this PVC-free picnic rugs better than the conventional ones (besides being toxin-free!) is that you can throw it in the washing machine to wash, and the grass doesn't stick onto the backing so easily like the ordinary picnic rugs do.