Small bags of fudge, biscuits etc.
Could you make small craft kits, e.g some cut out pieces of felt/material, wool and a darning needle - maybe a plastic one and some pot pouri or something like that to stuff them with.
Can you sew? You could run up some childrens aprons, bunting, dolls clothes.
Baking kits. A childs baking set from the £1 shop and a bag of the dry ingredients (flour and sugar etc). With the instructions to add the wet ingredients, so it becomes like one of those cake kit boxes you get in the supermarket - but more individual.
Make some pommanders/lavender bags.
Sell decorated candles. Buy some plain church or dinner candles and a bag of jewels/sequins and stick them on. Or dry some fruit out and stick those on for a natural look.
Dacorate a frame kit. A cheap plain unpainted photo frame and some stickers/glue/glitter for the children to decorate it with.
Or buy them and decorate them yourselves. Cover them with ripped up newspaper/magazines and apply with pva glue. Or paint with one colour, rub edges with a candle then paint with another colour, lighlty rub over the wax with sandpaper/wire wool so the base colour shows through for a shabby chic look.