Restaurants in Sevilla that serve Early Dinners

I don't know of specific restaurants - most do open later, as you noticed. However, there are cafes and tapas restaurants that serve food early. Many locals or tourists from other parts of Spain will be having something somewhat akin to "happy hour" at that time - a drink while sharing food. This could easily make a dinner if you order a few plates. These places are casual, may not have easy-to-find websites, and the food is not fancy. It's often very good, but just more simple than a traditional restaurant meal. Lots of ham, pan y tomate, simple grilled meats. You will walk by many in the historic core It's still seated at a table with a waiter (counter serve/fast food places would also be open if that's your thing).

I would suggest having your "main meal" at lunch - that way you can enjoy more traditional restaurants - and having a smaller dinner as described above.

Mira describes the strategy we have evolved for most of our days when traveling in Europe, not just Spain. Being in our ‘80’s, we have found that late dinners often lead to disturbed sleep. Even when restaurants officially open at 7 pm, often, in reality, 7:30 is when things really get going. That means eating at 8ish.
In Spain, hotels often offer elaborate breakfast buffets. We eat large breakfasts, and plan for a main meal lunch stop around 1 pm. Many restaurants have set meals or menus del dia available at midday. They are usually good value.

You can eat tapas earlier in the evening. Or, If there is any sort of refrigerator in your room, you can pick up foods for in-room picnics. Also, in cool weather that you are likely to experience, refrigeration probably isn’t necessary.

I did a quick search on Google maps and found a number that open early.

Close to Plaza Nueva
Taberna Coloniales. 12:30pm-midnight, c/Fernandez y Gonzalez
Casa Robles, noon-1am, c/ Alvarez Quintero
Torres y García, 1:30pm-12:30am, c/ Harinas
Casa de Extremadura de Sevilla, 8:30am-midnight, closed Sunday c/ Fernandez y Gonzalez

On Cartuja island
Sloppy Joe’s de los Remedios 1pm-1am on c/ Asuncion
Jaylu (seafood) noon-6pm, 8-midnight on Lopez de Gomara
El Rincon Trujillano 12:30-11pm Friday-Tuesday on Lopez de Gomara
Doner Kebap noon-5pm and 8:30-1am Av Santa Cecelia, Turkish
Asador los Tejares, 8:30am- 11pm
Gastronauta, 1-4pm, 8:30pm- midnight on C/ Esperanza de Triana
Tijuana Tex Mex 1pm-3am c/ Asunción

Of course there is a McDonalds and Burger King. There are many more. Just look for ones near where you’ll be staying

Go to this market
http://www.mercadodetrianasevilla.com/

Adding a vote for Taberna Coloniales above. Food was really good and atmosphere relaxed. We ate there twice at different times of the day.

Travelmom, is the Taberna Coloniales you went to the address that is listed above? I looked them up and there's another one nearby (appear to be same owners) at San Pedro. Thanks!

Mari, yes it was this one. It was busy both times my daughter and I went and we were seated upstairs (in case that matters). But it was fast, efficient, good (not “foodie” good), and pleasant. I would not mind taking a child. We always had 2 or 3 things from the tapas menu. I had a recommendation prior to our trip (maybe Rick’s book?) but we actually ate there the first time after asking a coffee shop employee for recommendations. But don’t worry about finding an early place - you won’t have any trouble.

Thank you all so much for your help! We were planning on making lunch the main meal anyway, and it sounds like we can just pop in for tapas and drinks when we get hungry in the early afternoon. We will definitely go to Taberna Coloniales. Thanks again!