You need a space between the id and the value attribute:
// --------------------------------------v
.append('<input type="button" id="'+id+ '" value="'+value+'">');
I also added double quotes around the attribute values, and removed the closing </input> tag.
This results in:
<input type="button" id="id" value="value">
...given "id" as the value of id, and "value" as the value of value.
The way you had it, the value of the id attribute, and the value attribute itself were merged, so if the value of id was "id", it would look like:
<input type="button" id=idvalue=value>