I've been meaning to ask as well about rose hip treat prep-and other herbs- I normally get mine from a health food store, but I've got some wild roses with hips I'd love to take and some other wild herbs too. I'd wait until the hips aren't green personally. Based on that I think they'd store better and have a crunch chins love- I don't know if they'd necessarily be bad green. Make sure the plant was never sprayed though- chemicals can stay within a plant for an extremely long time and can be toxic to chins, even in low doses.
For other treats:
There's quite a few healthy treats, most of the best are low in sugars and water content. The best are ones that are as similar to the chins diet as possible (some people even make chin cookies out of the hay and pellets) Some herbs make excellent treats but can have medicinal qualities so you've got to be careful with amounts. Moderation is key with all treats, make sure they're only having one small portion a day, or break what would be one even smaller. Remember how little goes into a chin- you dont want them to eat the treat and not have room for healthy food.
Some treats I've fed my chins that they love are red rose petals (other colors are safe too), oats (make sure they're old fashioned oat groats, not the instant kind of oats which can swell up after the chin eats them), an organic unsweetened Cherrios, a pinch of unsweetened Post shredded wheat, dried dandelion flowers can be nice but I only give them once a week or less, or I trick them by giving them a wood chew they love that they think is a treat. My chins get grapevine and poplar all the time, so pear, blackberry, or apple wood are all considered treats by them (and grapevine tendrils- I dont know whats special about them compared to the vine but the chins LOVE it). The awesome thing about feeding twigs is that you can feed as many as you want without health issues (as long as the chin still believes it to be a treat)
Im actually doing a treat taste test on some herbs right now- theres a thread in the general section I'll be adding as they taste more, it's a little slow because I dont want to intro them to new treats too fast in case one doesnt agree with them. I also am being careful as some of these should be infrequent treats, but are still nice occasionally. The list Ive gotten for mine includes:
Calendula flowers
Chamomile flower buds
dandelion root cut
Hawthorn berries-whole
Hawthorn (c/s which is cut and deseeded) flowers/leafs/stems
Hibiscus flowers
Jasmine flowers
Lavender flowers
Linden flowers
Nettle
Papaya leaf
peppermint leaf
raspberry leaf
red clover blossoms
strawberry leaf
pretty much everything is available either at a vendor on here or a local health food store.
oh yeah- a different hay than normal can be a nice treat. Timothy should be the main hay and you shouldn't feed the other hays enough that the timothy isn't eaten, but orchard grass or alfalfa can be a nice change of pace.
Some people will give their chins dehydrated fruits such as raisins, but they're so unhealthy and filled with sugar that's not good for the chins, plus I've found that my chins beg for certain safe treats and love them more. Why feed an unhealthy raisin that could cause issues when my chin loves a more healthy Cheerio better?
Hopefully I've covered all the treats. I really hope someone else chimes in on the harvesting hips thing.