I had a mare that like Cheez its. She would do anything for a cheez it. That same mare also loved dehydrated Pink Lady Apples. I would make them for a trail treat for me. We would be wandering down the trail I'd reach into the saddle bag to get a little piece of apple and she'd crane her head around and wait for her piece. She also liked beer.
I had a gelding who LOVED ice cubes. He wouldn't eat anything else out of your hands but an ice cube.
I agree with katarine about feeding them in a bucket first. I got a mare who was 5 when she came out of a field and was immediately stalled at the trainers. When she came to live with me she had no idea what a treat was.
She would refuse them from my hand and I would just toss hers in her feed bin when I gave some to the other horses. Gradually, she started eating them and will eat out of my hand. She prefers butterscotch flavor (I think the brand is Manna.) After a while she started eating from my hand. She still won't eat apples, carrots, or other treats which most horses go crazy for.
When we first got my mare, she didn't want to eat anything out of our hands. I think she'd just never really done that. My fiancé offered her Kashi Go Lean Crunch enough that she learned fast. Now we've totally ruined her and she acts like a whore begging for treats (especially from my fiancé who's a Pez dispenser in disguise).
Find something your horse likes and it's all downhill from there...
She eats grain from my hand no problem; so I don't think that's the issue. That's what I've been using as a "treat", but it's really not convenient, and not really big enough for neck stretches. I might just have to buy a bunch of stuff and see what will work. I've NEVER had a horse turn down Nicker Makers, and she won't eat those. My other horses will tear down the fences for those.
She might eat those sweet feed "muffin" type treats - I just hate buying them because they are expensive and you don't get very many in a container.
My horses all love Apple Wafers. As a substitute I started buying Cow Cubes - the larger size cube of the pelleted feed we used to buy. (Totally safe for horses.) They LOVE those now and they only cost like $8/50 pounds!! I think if I threw a handful of nuggests on the roof, all the horses would be on the roof!!
Meadow, ask your feed guy to find a larger-pellet grain for you. They DO exist! Then, you can give a single pellet per treat. It's much easier than a little handful of loose grain, with the horse trying to lick up every crumb. (Though, it's still not as good as a long carrot for those neck stretches.)
I'm sure it is very frustrating to try to do +R with a horse who doesn't want treats. I would be heartbroken!
One of mine will not eat any junk food, only apples and carrots. No peppermints, no watermelon, no chips, beer or soda. The other eats anything plus hot chocolate, coffee, orange soda and beer and he doesn't object to cigarette smoke. I think it was his race track training!
How about putting the pelleted feed in those little pastry puffs/crusts or making like a refridgerator cookie with the pelleted feed. There has got to be something you could use to hold them together. Even if they are a little sticky you could use those little cupcake papers to hold them in.
Mrs. Pastures. Then you can begin working down to the cheaper stuff.
Ha, ha, ha - my guys LOVE Mrs. Pastures. We tried to go the cheaper route with Dumor's from TSC. They ate them maybe 2 or 3 times and then flat-out refused to touch them ever again! I guess they figured that if they held out long enough we'd relent and buy them their coveted Mrs. Pastures (which we did, of course - always have a supply of Mrs. Pastures on hand now).
They also like Starlight mints, candy canes, those jelly candies (like the old Chuckles), and carrots. And people oatmeal cookies are good too!