Of course, tiggerblue is correct to the extent that the word "vegetable" isn't a class of life... it's a culinary or shopping term... at present there are five Kingdoms of life; Animalia, which is made up of animals; Plantae, which is made up of plants; Protista, which is made up of protists (single-celled creatures invisible to the human eye); Fungi, which is made up of mushrooms, mold, yeast, lichen, etc; and Monera, which is made up of the three types of bacteria. (For this discussion, we'll ignore the controversial archaebacteria".
Mushrooms are fungal in origin and as such cannot describe "vegetable", however one could correctly state "I bought vegetables today... lettuce, carrots and mushrooms..."
In my opinion...