You might have been exposed to the Flowering Pear - Pyrus calleryana - which has a potent smell of carrion (dead, rotting meat), and is pollinated by *flies*, and not by bees or butterflies.
The flies smell the carrion 'fragrance' and are attracted to it. It's the only plant with such a potent, powerful smell. I hate the damned things, personally.
They're way over used by builders as yard and street trees, grow fast, are weak wood and fall apart in ice and snow storms (especially the lousy Bradford Pear). There are several cultivars which are good: Cleveland Select, Aristocrat, Redspire and a few others.
This is a Flowering Pear, with similar flowers to the Flowering Cherry, but important diffs, as noted above:
