You are describing a Bold Jumping spider. Very common from the great plains to the east coast. Note the adults have white spots while the juveniles have the orange spots. Most easily Identified by the green/blue iridescent fangs or chelicerae. They are quite harmless, rarely bite humans and if they do, It only leave a slight redness and irritation.
I believe this spider friend of yours is a jumping spider, although there are lots of other spiders out there who are yellow, grey, black, orange and brown.
Ariel
A brown spider with a yellow stripe on its head is a wolf spider. The wolf spider may sometimes have an orange stripe on their head also.
Poisonous spiders are many different colors. The Black Widow is as the name states black with a red hourglass on the bottom of the abdomen. The Brown Widow is a light to dark brown spider that looks like the Black Widow only with patterns of brown. It too has a red hourglass on the bottom of the abdomen. The Brown Recluse Spider too is brown like the name states with a darker brown 'violin' marking on the cephalothorax. The Hobo spider is light brown with a darker brown abdomen and a cream colored strip going down the center of the cephalothorax. Yellow Sack Spiders are usually yellow or creamy colored. The Brazilian Wandering Spider is a dark brown spider and usually have red hairs on their chelicerae.
wolf
The distinguishing feature of a brown spider with a black head is the contrast between the brown body and the black head.
The spider you are referring to is likely the yellow sac spider. Yellow sac spiders are brown with two yellow stripes on their back and are commonly found in California. They are not considered aggressive towards humans but can deliver a painful bite if provoked.
Spider is light brown with gold or yellow diamond back
The spider with brown and black stripes on its body is commonly known as the "garden spider" or "Argiope aurantia."
Spiders are all colors (and they change color when the moult to camouflage themselves better!)
A black spider with a brown stripe has a distinctive marking that sets it apart from other spiders.
The distinctive appearance of a brown spider with black and white stripes includes a brown body with alternating black and white stripes on its legs.