We have a huge hedgie visiting our garden every night, making a beeline straight for the tray containing dropped sunflower hearts from the bird feeder above. This won't harm him will it, as he seems to love them! I know Mrs Tiggiewinkles hedgehog hospital recommend not letting them eat peanuts but I'm not sure about sunflower seed hearts.
I can't claim to be an expert, but if you had sunflowers planted in your garden, you wouldn't be able to stop hedgehogs scavenging around them - so I guess it's ok?
I hadn't thought that our hedgehogs were after the dropped sunflower seed hearts though when I think about it they tend to lurk in the vicinity of the bird feeders. There's also little mouse who dashes out from under an old bench in the corner of our garden to pick up the dropped seeds as well - I hope someone on here knows about the seed hearts and if they are bad for the hoggies. Failing that we'll need to get in touch with St. Tiggywinkles.
We actually have a hedgehog house and we put out dried worms and chicken cat food. They come every night and really tuck into the chicken cat food and will eat the worms after the cat food has been devoured. Hubby put in a small camera so we can see it feed! They are very cute!
Just read that sunflower hearts are a tasty snack for hedgehogs and as Naomi said, if they were natural in your garden (and you weren't observing them eating) then they'd eat them anyway.