"The Amish really don’t like compliments. So, by saying your vegetables look better than the other Amish family, you aren’t really complimenting them. They are a humble people and work at being humble."

So maybe they don't like having things like that done for them?

Regardless, their beliefs aren't your fault. You did a good thing. Other people can't be expected to know that they reject that sort of thing on religious grounds.