It's coming up to the time of year to collect seeds from crab apples if you'd like to grow trees.
Find your favoured tree - I have my eye on a friend's, which has bright red apples from around August, and those apples are absitively delicious.
Open some apples till you find nice-looking seeds, fat and brown. Take out the seeds (with clean hands) and put them on a clean damp tissue sprinkled with powdered cinnamon. Mould hates cinnamon.
Fold the tissue over and put it in a clean plastic sandwich bag, and put it in the fridge for a few weeks. Maybe put it in a jar so it doesn't get jars and things put on top of it by mistake by Certain Parties who also use that fridge.
Last year I forgot about the seeds till spring, when they had nice long sprouts. I put these in a sandy compost mix (about 2/3 compost and 1/3 horticultural sand - don't use builder's sand, it's salty and kills plants) and three of the 15 or so sprouting seeds I had grew on into little trees, which are now around 40cm tall. With luck they'll produce crab apples four years from now.
There's something so life-affirming about growing a tree from seed.