They are cucamelons.

https://practicalselfreliance.com/growing-cucamelons/

When I looked at tour photo that was exactly what I was going to ask, LOL. Glad Amylou knew, I don't think I have ever seen them here.

A.k.a. Mexican sour gherkins...?

https://www.southernexposure.com/products/mexican-sour-gherkin-mouse-melon-sandita/

Now I want to try growing them!

Lovely display. I thought they were small watermelon radishes. Now that I know what they I want some!!

I grew some one year, didn't love them, but they're interesting. Might be good pickled.

I just found them in the current Seeds 'nSuch catalog. They have them listed as 'Mexican Sour Gherkins' - description: "Sweet flavor is contrasted by an unexpected sourness, as if they've already been pickled." Sounds rather intriguing!

Yes, Mexican Sour Gherkins. I found them difficult to grow, I think it's not hot enough for them here in Michigan, and no one in the family would eat them, they disliked the sour flavor but they were very neat looking, like tiny little watermelons.

Annie

Now I do want to grow them; it sounds as if it might be possible here in CA. I’ve never seen them in the grocery, which is surprising. The photo was taken in SoCal, so maybe they are more popular down there.

I'm in So Cal and have never seen them! Maybe they're more prevalent in the So Cal Los Angeles area. The most exciting "new" thing in our stores since a few years ago are Moon Grapes (aka Moon Drop Grapes).

I haven't had Moon Grapes, but I do like pink (rose) pineapple.

ETA - just googled, yes I have had them. They are tasty but kinda ugly!

I grew these a few years back. They didn’t do too well because someone that promised to keep them watered didn’t. Can’t recall how good or not they were, I should try growing them again.

I'm also in SoCal and have not seen or heard of them. Definitely DO look like tiny watermelons.