Here is a free pattern from Meighen.
The Mexico Market Bag
Row 1: 10hdc in magic circle
Row 2: 2hdc in each hdc around (20)
Row 3: 1hdc in first and 2hdc in next repeat around (30)
Row 4: 1hdc in first 2 and 2hdc in third repeat around (40)
Row 5: 1hdc in first 3 and 2hdc in fourth repeat around (50)
Row 6: 1hdc in first 4 and 2hdc in fifth repeat around (60)
Row 7: ch4 (counts as first tr throughout), tr in second sp from ch, *ch1, skip sp, tr in next sp *repeat around and join in 3rd ch of ch4 (30)
Row 8-16: ch4, *tr in next ch sp, ch1 *repeat around and join in 3rd ch of ch4 (30)
Row 17: ch1(does not count as hdc), 2hdc in ea ch1 sp (60)
Row 18-19: ch1, hdc around (60)
Row 20: ch1, hdc in same and next 9 sts, ch1, turn (10)
Continue with 10 hdc turning each row until you have enough length for the strap. Count 20 sts from the beginning of the strap around the top of the bag and connect. You can use a sc, sl st, or a yarn needle. Whatever you prefer.