Sun shelter over grass areas

A lot of parks do not have adequate shade covering play areas (especially metal slides that become so hot they cause serious burns on unsuspecting toddlers!) but I would also love shaded areas on grass or surrounding the park so I can lay out a picnic rug for my baby whilst my toddler plays. Coverings over picnic benches are good but often they aren't being used as most parents with babies have to have space for their bubs to wander. Leafy trees or sun sails would be ideal :-)