Are you talking about the pickled yellow peppers a lot of burger places serve?
If so it's probably Guarrito Peppers.

{{gwi:1151711}}

They get red when ripe but are usually pickled yellow.
Can also be Cascabella peppers too.
They might be the same thing....

Or maybe sweet banana peppers or Hot hungarian wax peppers. They are usually cut into ring shapes and are almost always yellow.
Bruce

Smokemaster, I think that's it! Thanks! They were whole, not cut into rings.

By the way, Smokemaster, thank you so much for all your generous contributions to Heather's seed swap. I received a lot of wonderful peppers with your label. Really appreciate it.