There are so many pretty plants and wildflowers along the roadside right now. How can I learn which ones would make a good flower garden without the neighbors thinking I have a weed bed?

you can go to your local flower/landscape center for starters (not a chain store where generally the assistants are usually not educated on plants)... or could research the plants you like... also, most states have a chapter of 'Wild ones'.. an excellent resource.. or any native plant growers, retailers in your area.. or your local botanical gardens... as far as your garden looking neat rather than a 'weed bed', just design it well, maintain it well (keeping things cut back and weed free), maybe mulch it... actually, your neighbors will probably love it, it would be something not everyone else has and attract so many butterflies and birds that they'll all want it too

Your state or one of your surrounding states that are in the same gardening zone as you are should be a good resource for you. Also, there are often smaller garden centers that specialize in native plants and they are often very happy to provide advice.

try searching with key words such as : native plants - horticulture -and then name of your state. or gardening with native plants and the name of your state.