I will try to give this some thought Susan as I have not had this before. DBS has some rodeo redwork I think they do

Adorable Applique has cars, and animals that would work well for a little boy. SICK has Koala Bears, and motorcycles. How about his first name initial using the Robot Font on Cute! Dogs, horses and trains might also be an idea. Hope this helps.

Jazzy Zebra has quite a few RW/CW designs for boys

http://www.jazzyzebra.com/redwork/colorwork-designs/

DBS has fun All Terrain Trucks.

Designs by Sick has all those great old muscle cars and motorcycles.

Football, cars, airplanes, helicopters,motorcycles,animals. I've been doing boys designs the longest (grandson is 15) There are thousands, maybe not redwork, but boy designs. My favorite are appliques.

You have to 'look' harder to spot what is suitable for a boy. Sometimes it is just a matter of changing a colour or three.
There is a bigger market for girlee things. I do not know why as 50% of the population is male.
Brother has a Penny Farthing bicycle that is one colour and I am sure that I have seen it (or similar) by other companies too.

I run into this now with the 7 yr old Great G/ son. He is past the age for anything cartoony of animals , animals and such, he informs me he is not a baby anymore, but the 4 yr old sis tells me the same thing. He plays ball and has for 2 yrs now so anything I can find suitable for ball playing I can please him with and he loves to swim so that's another area I can please him with. He loves and has 2 dogs so that pleases him if it looks like one of his dogs. He is very opinionated about his initials, always wants all 3 and in a row, doesn't like the last initial in middle. LOL The little ballerina I can please as long as it is not babyish.

Bunnycup Embroidery. Type into the Search area "Just for boys redwork"
There are 2 sets Sporty Boys. Click on one and you will see 12 designs in each set. On sale for less than a dollar per design.
Remember 5yr olds love animals, dinosaurs, bugs, robots, and all kinds of sports.

There is a free redwork set (10 designs) of Boys fishing at Kiwi...you will have to log in or sign up for newsletter to access Freebies...but this set is on Page 4...lots of other Boy redwork sets for sale, too.