Problem with SELECT statement

[dsalada]

I have run across a very interesting problem with MySQL. I've never seen anything like this before. Any info about what might be going on would be greatly appreciated. Here is the problem. When executing the SQL statement:

select material_type from TABLE where material_type like '%textbook%';

I get the following results:

+-------------------------------------------------+
| material_type |
+-------------------------------------------------+
| Book |
| ::Textbook::Workbook |
| Textbook::Video_Material::Workbook |
| Textbook |
| Textbook |
| Instructional_Material::Textbook |
| Teaching_Guide::Textbook::Video_Material|
+-------------------------------------------------+

The problem is that the first record returned doesn't contain 'textbook' in it at all - just 'book'. I haven't had this happen with any other queries using different words and the same column. I'm not sure what to make of it. Any help would be great.