My friend got back to me. She said that it was quite by accident that her bunnies got a taste of pumpkin at first. She had one out as a decoration (the large ones), then found a bunny nibbling on it. She did some research and found that it's safe for bunnies to eat. So she let them nibble and eat the outside and the pumpkin flesh, but not the stringy insides and seeds. She would turn the pumpkin around so that they could eat some more of the outside and keep them away from the insides. Then she would take it away when most of the outside was gone
I just did a search on pumpkins and rabbits and found this link which lists pumpkin as a rabbit safe vegetable. (I thought it was a fruit). Scroll down, pumpkin is listed with the squashes. I don't know how old this web page is, but it was written with a consultation by a vet.
Here is another website that lists pumpkin as safe, this time it's on the fruit list. This list came from Rabbits for Dummies 2nd Edition and from personal experience of the writer, who is a bunny mom.
I'm not advocating that anyone go out and buy a pumpkin for their rabbit to chew on and/or eat, but I thought I would let you know the info that I found. I would definitely keep those mini pumpkins away from them, the ones that are usually sold with gourds, since they seem like they could be coated with something.