Last summer, I made this very quick & easy collecting bag for my little guy. He loves to take walks and loves to collect things (don’t all little ones?), so he needed a bag for gathering up his treasures as we walked. I let him pick out any fabric he wanted from my stash and he picked this London themed cotton flannel. If your little one tends to pick up wet or gooey things, I would suggest a fabric like oilcloth, because it is very wipe-able. Since a bag for treasures is no where near as much fun as a bag for treasures that you can see into, I did a see-through front with some clear vinyl I got at Joann Fabrics.
Basically all I did was cut out two identical rectangles from my print fabric and hem the top edge on both. Then on the front piece, I cut out an opening from the middle, to be my see-through window. I stitched on the plastic to cover the hole. Then I put right sides together and sewed the front and back pieces together, boxing the bottom corners. For the strap, I just used cotton webbing they sell by the yard at the fabric store. Voila! A collecting bag done in about an hour, if that.