What flowers can I put in my flowerbed that is in the sun all day

My favorite is daylilies, but Lantana, Mums, any perennial that is full sun as well as hardy annuals. Find out your US last frost zone and google "best flowers for full sun". You will have reading material for days because there are thousands but it depends on where you live and what your planting zone is.

My vote is for daylillies too. Geraniums are always fun.

Kalueke is right about checking which growing area you're in and planting accordingly. Here in South Carolina (coastal region) the soil is either sandy or clay, and the heat and sun can be fatal to plants in the summer. I've had the best luck with daylilies, chocolate mint, ice plant, coreopsis, roses, and marigolds.

Daisies, yarrow, coneflowers and lavender all do well in full sun. Verbena, aster and lamb's ear also thrive in the sun. And the list goes on. Out of all of these, lamb's ear is my favorite. Best of luck to you.

check at your local garden center.. they usually have the ones that like full hot sun in that setting. Just wander around and read the tags.. in each pot.. even seed packets will say full sun, part sun full shade, etc