The underside of a spinach leaf makes a fine place for a spider to guard her egg sac, right up until the leaf arrives on the kitchen cutting board just before breakfast:
We deported her (and her incipient family) to the flower garden just outside, wished her well, and continued with breakfast.
The Smell of Molten Projects in the Morning 
Ya done good!
Looks like a pisarina mura or nursery web spider
Auto correct wrong again that was intended to be pisaurina mira
Thanks for the ID! It’s always good to have a name for things found around the house … [grin]