It's the time of year when quite a lot of herb and salad plants are setting seed- and lots of flowers, too. While letting them self-seed all over the garden or allotment can be a good option, it can be useful to save seed as well- either to plant in known locations, or to give away.
This is a really quick and easy thing to do.
Take the section of plant with the seeds formed and already drying out on it (this can be the whole plant in the case of lots of salad plants once they've bolted) and hang it upside down in a breathable bag- this can be paper or cloth, but not a plastic bag as the seeds will tend to stay damp and rot.
Above we've got mixed salad plants in pillowcases- the pillowcases don't get damaged by doing this and it's an easy way to catch a lot of seeds!
Make sure that the seed pods are starting to brown before you collect them - immature seeds from green pods may not be able to grow when you plant them.
Hang the seeds somewhere dry- a garage, shed, kitchen, utility room, bedroom, wherever you have space, and once the plants are properly dried out give them a big shake and maybe a scrunch too, if the seeds don't come loose easily. Then tip the seeds into envelopes, small bags or a plastic tub and save them somewhere cool and dry until you want to plant them. Put the waste dried plant bits into your compost.
Most seeds last for a few years at least before they stop germinating- but some species can be trickier than others.
This isn't a professional operation- it doesn't matter if you end up with bits of dry stalk, leaf or seedpod in with your stored seeds, or if you lose some seeds along the way- the ones you have will still grow fine even with extra bits in there- just as they would if they fell from the plant naturally outside.
With things like salad, you can re-sow the seeds straight away for another crop- and keep going all year, if you have a handy windowsill or greenhouse!
Fun seed heads for kids include things like poppies and peas, sunflowers and - poppies have great seedshaker pepperpot heads and peas and beans just feel nice, while there's something really satisfying about pushing the seeds all off a sunflower head with your thumbs.