Bananas are fun. Get the ripe ones, remove the skins and freeze for 45 mins or so to firm them up first. Relax your sphincter with fingers / dildo etc and then a quick dip in water and you should be able to easily insert ½ at a time. Marvelous sensation of fullness. If you hold them for a while they will pretty much dissolve. Mild cramps. I read about people using slightly under ripe bananas and injecting them or coating them with glycerin to up the urgency factor.
I read the following thread a while back, but it sounds way more intense than anything I'd want to try:
https://en.zity.biz/index.php?mx=forum;ox=display;msg=848472
Baby potatoes are nice (nice and spherical), but I once had a scary experience with them where one didn't immediately come out! Nature took care of things for me in due course! No need to panic!
Grapes/cherry tomatoes are fun. Again, have read about people injecting them with glycerin, but never tried it.
Marshmallows were once used on me, they'd been dried out some and were firm. A quick dip in some water and they became slippery and easy to insert. I took about 15 of them before massive cramps hit and they all came back out in a torrent! Also expelled a lot of mucus for a while after and didn't feel great. Probably not a good idea if you are diabetic.
Ice cubes have been fun on occasion. I like the cold sensation and periodically you will feel the cool water move around inside as they melt. I'm fortunate in having a tabletop icemaker which makes ice which is surprisingly suppository shaped! It's soft ice (wet on the outside) and melts fast which is nice for that application.
https://www.amazon.com/Countertop-Ice-Maker-Machine-Indicator/dp/B099VTYY7L/ref=sr_1_40?dchild=1
Never had luck with hard boiled eggs (peeled) which just broke up for me.
I looked at avocado pit and wondered, but never tried it yet.
Once tried computer mouse balls (they were throwing out a load of mice at work). They were basically large ball bearings with a rubber coating and I thought the weight would be good. I removed the balls and washed them thoroughly and then put them several into each of the fingers of a latex glove, giving me some control of making sure they didn't get lost inside. They were large enough to stretch the fingers which then held the balls in place in the fingers. After adding some lube to the outside of the glove, I could pop each finger in one at a time and leave the wrist part sticking out for easy removal (or so I thought). Once in, they gave a sensation of heavyness and I could feel them pushing against my prostate which felt great and after wandering around doing chores etc for an hours or so resulted in a continual stream of precum. When I came to remove them, you might think it would have been just a tug on the glove, but if you pay attention to a glove, all the fingers are roughly parallel, and so all wanted out at the same time and it was quite challenging to remove them…..won't be trying that again!
Someone posted early on about fruit including pineapple and though I haven't tried pineapple, I'd suggest avoiding it because it contains Bromelain which is an enzyme that is used as a meat tenderizer, can burn your tongue and overtime will chemically dissolve meat. I'm thinking that's probably not good for your insides and could be hard to explain in the ER! I had chemical burns on my fingers once from cutting up pineapples (wife was canning them and we got 30 from Aldi's on sale), they started off sore and after I finished I'd washed my hands well, but the next day the skin split and bled and was very sore for the better part of a week.