The sunflower seeds in my salad come from an achene. And look at the samaras on the maple tree in the courtyard, they are essentially winged achenes. And your strawberry is a collection of a bunch of achenes. It's an aggregate fruit that came from a single flower with numerous carpels. The flower had an apocarpous gynoecium.
Pineapples are juicy fruits.
You know, like they use to make gum. Multiple fruits are derived from ovaries in many flowers. As they develop the ovaries fuse together. It's easy to see on a pineapple. Each of the different sections represents a flower.