Echoing what John said.
I saved seed from F1 hybrid squashes and pumpkins the year before last. Sowed them last year just to see what came up. About 50% germinated and went on to produce decent plants. The pumpkins however produced NO fruit. The squashes produced a mix, some like the parent but many not so, small fruits but still tasty.
Last year I saved some melon seeds. So far, similar story - 50% germination.
Tomatoes pop up everywhere and they were from F1 hybrids.
But I've saved seed from many F1 hybrid flowers and got 0% germination.
Hybridisation does take place naturally when
bees etc visit many flowers BUT in a natural situation it doesn't generally lead to heavy inbreeding which is what happens when they're producing F1 hybrid seed.
The guys who produce F1 hybrid seed are in the main doing it for the commercial grower so that the crop ripens all at the same time for harvest, or has uniform shape etc etc mostly because the produce is going to supermarkets where consumers (so they say) demand that all their apples/carrots/leeks look the same with no 'unatural' twisty, lumpy bits. Flavour seems to be VERY secondary.
I have now stopped buying F1 hybrid seed as, now that I know, I am primarily against the exploitation of the third world on seed circles. As a happy accident I get crops that are more suited for our needs - crops that year on year will adapt to my soil and situation as they have a broad genetic base. The 'Company' that I get mine from (two people working off their kitchen worktop) made me laugh when they gave a list of the 'wonderful benefits' claimed on the backs of some seed packets and their translations....
Good for freezing - ripens all at once so you get a glut
Straight long shanks - bred for the packing machine
Leafless peas so easy to find the peas - much smaller yield (there's no leaves to
feed the plant!!!) but miles easier to harvest with a combine.