Does anybody know of any plants that have more than one kind of fruit?

Grafted "fruit cocktail" trees.

Sure, if one grafts a bunch of different fruit trees on to one rootstock. Imagine different kind of Apple scions on one root stock, or different Citrus, or Plum tree onto Apple etc.

ummm, don't think you could graft a plum onto an apple.

I don't know if it's considered fruit or not, but there's a plant called hog peanut that grows where I used to live, and it gets 2 different flowers on it, and makes a "peanut" under the ground, and something like little bean pods above ground. I was wondering if there are other plants like that. I've tried doing searches online, but I'm not getting anywhere.

There are many plants that have both male and female flowers. Some don't produce anything on the male flower, but others (some palms for example) do produce something similar to seed, but not fruit. Sounds like your "hog peanut". I know this because my Queen palm is shedding male seed and blossoms as I type...the fruits will follow all to soon.

Thanks Carol.